MLB DFS 2021 Preview - Preparing For A New Season

Happy Spring! Welcome back to baseball season here at RotoGrinders. After a shortened 2020 season, I am more than ready to get back to some sort of baseball normalcy.

I have several articles from the pre-pandemic early spring of 2020 that can help get you prepped for this season. If you want an in-depth look into the stats to know and how I use them in my daily process, check out these articles, which walk through the analysis of both pitching and hitting stats:

Pitching Stats Analysis

Hitting Stats Analysis

For 2021, while we’ve got a full season ahead, there are some unknowns and new challenges. If you’re playing season long fantasy baseball this year, there are many more question marks, but for DFS, a lot of the mystery will be solved for us day by day. There will likely be some COVID related trouble in the first month of the season, but hopefully that will be over by summer. Plus, if a player is going to miss a week of games, we’ll know about it ahead of time, and we’ll have daily lineups known ahead of time. This is similar to the ever-present injury problems around the league. It’s a big deal in season long, but for DFS, all we need to know is who is playing that day. All this is to say that I am not going to stress out about COVID, injuries, playing time, etc.

There have also been plenty of roster changes that you might have missed if you haven’t been paying attention in the off-season. While I always prefer to be on top of all the information, the fact is that if you aren’t preparing for a season long draft, it’s really OK that you don’t know every team’s depth chart off the top of your head. For DFS, we’ll see the lineup before the game, and you’ll have the player’s stats on PlateIQ, and you’ll be ready to go. It might come as a surprise the first time you see Joc Pederson playing left field for the Cubs instead of Kyle Schwarber, who it turns out is in the Nationals outfield, but really, are they even different people? I’d recommend taking a look at the off-season changes if you haven’t, but you don’t need me writing an article about them.

But, if you know me, you know I’m going to stress out about something, so what will that be? I see two main factors that will make or break this season in DFS. First is how we treat the 2020 stats in such a small sample size. Second is how to account for the changes being made to the baseball itself in 2021. MLB has announced that the balls will be ‘deadened’ this season, but beyond that, this is all a huge question mark, but with extreme potential consequences for DFS. Let’s take a deeper look at these two areas.

2020 – Did It Happen?

Let’s start with the stats from the shortened season and what to do with them. Here are some examples of the nonsense we are trying to sort through:


Austin Meadows 2019 – 591 PA, .380 wOBA, .268 ISO, 22.2% K, .291 AVG with a HR every 16 AB

Austin Meadows 2020 – 152 PA, .292 wOBA, .167 ISO, 32.9% K, .20 AVG with a HR every 33 AB

So, is Meadows bad now after 36 games of a season where he missed the first two weeks with COVID and then played for a month before going on the IL with a sore oblique? Almost certainly not. But then does that mean we can just ignore that he struck out 33% of the time in his shortened 2020 season and assume he’s just the same guy he was in 2019? Well friends, that is where we run into the trouble. In cases like Meadows, I think we could just write it off completely and say 2020 never happened, but then not all cases are that simple. If we try to go case by case and give some players a complete pass on 2020 but then assume the data is real, for better or worse, on other players, then we’re bound to fall for a lot of personal bias.

Javier Baez 2019 – 561 PA, .347 wOBA, .250 ISO, 27.8% K, .281 AVG with a HR every 18.3 AB

Javier Baez 2020 – 235 PA, .256 wOBA, .158 ISO, 31.9% K, .203 AVG with a HR every 27.8 AB

Unlike Meadows, we can’t easily blame injuries or illness for this drop-off. Baez played every day, he just didn’t play as well. Or did he? Let’s check in with our old friend Mr. BABIP.

Javier Baez BABIP by season: 2016 – .336, 2017 – .345, 2018 – .347, 2019 – .345, 2020 – .262

It doesn’t take a rocket surgeonologist to spot the outlier. Sure, he struck out slightly more and walked a little less than his usual, but it could just be 60 games where things weren’t going his way. Or, maybe not. Yippee!! This happens over and over and over when looking at players stat lines between their historical numbers and the shortened 2020 season.

Some players saw a surge in skills, or a surge in results in the short season, while some saw the opposite. There are so many reasons any of these changes could have happened, and the bottom line is some of them are real, and some of them are not.

With hitters, as I go over and over all these different players, along with what we already know about necessary sample sizes for stats, I come to the same conclusion. I will be combining 2019-2020 stats into one long season, and not treating 2020 as its own season. So, I guess that means it sort of didn’t happen? More accurately, this means that since it was basically 33% of a season, I will be weighing it as tacking on an additional 33% to 2019.

Please note that this doesn’t mean you have to see things the same way I do, and if you want to try and decipher which players 2020 should be counted as ‘real,’ you are welcome to do so. I will certainly be talking through different situations as this year gets underway, but as far as looking back at a player’s stats, I’m not counting 2020 as its own season.

Most of what I’ve said above is relating to hitters. This is because of the number of games and at bats needed for hitters to reach a useful sample size. Because pitchers face so many more batters in one game, and can make noticeable, identifiable changes in a short period of time, I am more willing to buy into changes that we saw in a shortened 2020. But I want to be careful not to overdo it. Adding to the troubles is the fact that if a pitcher saw an increase or decrease in velocity in 2020, we can’t be certain that it wasn’t due to either the fewer number of starts or the stop and go, unusual ramp up to the season. If you’ve read the Musings over the past several years, you’ll know that I’m more willing to change my opinion of a pitcher quickly if he either changes his pitch type or velocity. However, there still needs to be some sort of baseline to start from, and I will come back to the same place as I landed with the hitters. If forced to make a rule to go off for the entire league, I will still be combining 2019-2020 as one season for a pitcher. If he did make significant changes in 2020, those changes will show up in the data, but not drastically enough to assume he’s a completely different pitcher than we’ve seen in the past.

A few examples:


Joe Musgrove 2019 – 170 IP, 21.9% K, 5.4% BB, 12% SwK
Joe Musgrove 2020 – 39 IP, 33.1% K, 9.6% BB, 14.4% SwK

Long-time readers will know that I have always loved Musgrove, and have been waiting for a breakout. But, cut it out. He had never topped a 22% K rate in four major league seasons, then all of a sudden jumps all the way to 33% in just eight starts. Other than an increase from 10-20% in curveball usage, there is nothing that changed dramatically in Musgrove’s game. I still love the guy, but it would be absurd to call him a 33% K pitcher based on 8 starts. Combine the seasons, and we are incorporating some of his strikeout gains from the short season but without giving it too much weight.

On the flip side:

Patrick Corbin 2019 – 202 IP, 28.5% K, 8.4% BB, 14.2% SwK
Patrick Corbin 2020 – 65 IP, 20.3% K, 6.1% BB, 10.6% SwK

Corbin had back-to-back seasons, over 400 innings, with a strikeout rate between 28.5-30.8%. Then it falls all the way to 20.3% in 11 starts in the shortened season. Where it gets murky is that I can certainly find a reason why he struggled. His velocity went from 91.9 in 2019 to 90.2 in 2020 and his slider was much less effective than usual. But the question is why? Is it because he’s getting older and losing effectiveness? Maybe, sure. Or is it because he pitched into late October in 2019, then started a normal spring training in February, before being stopped in mid-March, then had to re-ramp up in July? Maybe, sure. We simply aren’t going to know where Corbin lands with either the strikeout rate or the velocity until we see him pitching this season after a normal spring training. We’ll adjust quickly as the season gets going, but for starters, 2019-2020 was one season for me.


DISCLAIMER – After proofreading my own article (the first time I’ve ever done this?), I realize I need to start this section with a disclaimer. It is entirely possible that these new baseballs have only a very minor effect on the game and that it wouldn’t even be noticed in a one-day sample size for DFS players. I am making it sound like there is going to be some Titanic (great movie!) shift in the game with the league leader hitting 10 home runs this season. This is not the case. Maybe this is much ado about almost nothing, but I am just looking at the possibilities and how to be ahead of the curve here in the case that we see a bigger shift than most are anticipating. And now, on with the original story:

As tricky as it is to figure out what to do with the small sample size 2020 stats, in my eyes that pales in comparison to what happens to the actual baseball this season. All we have right now are these vague statements that MLB is slightly deadening the balls this season. This could be anywhere from a small, barely noticeable change, to a game altering shift that completely changes how we play DFS.

Just a quick recap, here are the HR/FB% (home run per fly ball rates) over the past decade:

2010 – 9.4%
2011 – 9.7%
2012 – 11.3%
2013 – 10.5%
2014 – 9.5%
2015 – 11.4%
2016 – 12.8%
2017 – 13.7%
2018 – 12.7%
2019 – 15.3%
2020 – 14.8%

There has been much debate and research done to determine if/when the baseballs were deliberately changed, and to what extent that caused the home run increase since 2016. What we do know, based on several studies, is that there was a change in the balls sometime in 2015-2016, which even MLB acknowledged. The issue resurfaced with vigor (resurfaced with vigor! Words!) in 2019 with an even bigger surge in home runs. There has been no argument from anyone that the balls have been ‘juiced’ over the past couple seasons, but nobody can tell us exactly how or how much or how intentionally. And herein lies the problem – we know MLB can change the baseballs to make them more or less ‘juicy,’ but we don’t know exactly how much control they have over the degrees of the change.

To be clear, the reason the HR/FB% was under 10% a decade and is up to 15% now is not entirely about the balls, but also the way players are being instructed to swing for the fences, giving up contact in the pursuit of power. But the ball has absolutely played a huge role in this, and if it is just suddenly different, the scoring environment in the league could be in for a rude awakening.

The good news is that we will be able to determine what is happening with the baseballs fairly quickly into the season, so long as they don’t switch up mid-season. If you read through hundreds of articles about this topic (I don’t recommend that unless you are extremely bored, and even then, it’s probably too many), it becomes clear that nobody knows yet exactly what these new balls will do to the distance of fly balls. The general consensus is that we’re looking at something like a 5% decrease in home runs overall, and something like losing two feet of distance per fly ball. If that’s all it is, it may not sound like a lot, but to me, it’s a lot. I’ll dig in a little more as we go along here.

The big question for us is what, if anything, does this change for DFS? My opinion at this point is that is changes everything, and potentially more drastically than most people will anticipate, although that remains to be seen. I am going to attempt to be ahead of the curve on this, and in the first couple weeks of the season, I will be building lineups under the assumption that home runs are coming down. If that turns out not to be the case, or if it’s just a minor change, then I’ll re-adjust. Here are a couple areas I’m specifically looking into.

1) Boost to Fly Ball Pitchers


If you’ve rostered Matt Boyd any time in the past couple seasons, you already know it’s been unsafe to park your car anywhere near Comerica Park on gameday. Pitchers like Boyd will not stop allowing home runs, but there’s a seismic difference between his 11.2% HR/FB from 2018 and his 18.2% rate in 2019.
Fly ball pitchers have high variance, and will continue to. It’s not as if home runs are going to disappear, but even a slight decrease in fly ball distance home runs could mean not just a run or two fewer here or there, but also an inning or two longer here or there. There will still be nothing more important or more projectable than strikeouts and walks, and that is still where we’ll start. I’ll look for that bias that some people may hold against the Matt Boyds of the world in the early going this season. I’ll also note that this could also end up being a big uptick for pitchers who don’t even need the help to begin with like Boyd does. The Top 15 pitchers in FB% in 2019-2020 include names like Gerrit Cole, Max Scherzer, Trevor Bauer and Lucas Giolito.

2) Could Fewer Homers Lead To Double Stacking?

Stacking in tournaments has been a thing and it’s still going to be a thing, regardless of the baseball. The less homer-friendly the ball, the more I will employ stacks. But even more so, I would be looking to more double stacks if it becomes harder to chase home runs. My default setting the past couple seasons has been to target only home runs with players who are not part of my main stack. That will not change, except that if the ball is deadened, then the affordable players with only moderate power will not be as enticing.

As an example, if Fernando Tatis, with his league high exit velocity and hard hit rate, gets a hold of one, it’s going to be a home run, regardless of whether the ball is deader or not. But what about Brian Anderson? (I don’t mean to pick on Anderson, surely a nice dude). While Tatis had a 55% hard hit rate and 95.9-mph exit velocity, Anderson was at a fine, but not great 35.6% hard hit rate and 87.4-mph exit velocity. Anderson’s exit velocity on fly balls in 2020 was just 77th in the league, but he still managed 11 HR in just 200 AB. Many of these are ball-aided home runs.

Here is where we’ll pause for a deeper look into why it would even matter if all we’re talking about is 2-3 feet distance on fly balls or 5% overall or anything in that vicinity, without even worrying about the possibility that it could be more than this. When I mention a player like Brian Anderson as candidate to lose some power, he’s not anywhere near the bottom of the list on guys who have been aided by the juiced ball. Looking at 2020 stats, here are a few players to consider, with their Average HR Distance:

Brian Anderson – 391 ft
Jean Segura – 387 ft
Anthony Rizzo – 386 ft
Robbie Grossman – 379 ft
Jorge Polanco – 378 ft
DJ LeMahieu – 361 ft

When we look at ballpark dimensions, straight down the line at any ballpark is an average of 330 feet, while centerfield is around 400 feet. The power alleys in right and left center vary by ballpark, but typically land around 360-370 feet. You can already see the issue here I’m sure. But we also need to remember that a home run is not given for hitting the ball over a line drawn in the dirt. It’s a wall or a fence. A fly ball that lands 391 feet for Anderson means it fell to its low point after 391 feet, but it was falling from its peak long before that. Meaning, a fence does not need to be 391 feet to stop Anderson’s home run. When you start looking around MLB at outfield wall heights, you’ll find they are all over the map. Obviously, something like the Green Monster in Fenway affects everything about batted balls, but there are other walls over 20 feet tall in places like Arizona, San Francisco and Baltimore.

Let’s take Anthony Rizzo as an example here. 386 feet as an average home run means some went further, some were shorter. Straight down the line in right field at Wrigley is 353 feet, he should be OK if he hugs the corner. But the power alley in Right-Center is 368 feet, going up to 400 feet in Center. But it’s not just the 368 feet- there’s an 11-foot wall. By the time a 386-foot fly ball has traveled 368 feet, it’s not still going up (hello Science?), it’s coming down. Start looking at all these home run distances for all these players and then looking at park dimensions and wall heights, mostly in the power alleys, there is no way we don’t lose at least a few home runs this season, even if it’s as small a change as 2 feet per fly ball. But a reminder, this 2 feet per fly ball is a random guess, and it would be more or less based on the exit velocity and launch angle of each individual hit.

Now back to the original point with the example of Tatis and Anderson. For DFS purposes, a superstar like Tatis is always going to cost top dollar, and we can’t just fill out a roster with Tatis, Trout and Cruz around a stack. It’s the players like Anderson and continuing down from there who become affordable to round out our lineups. In a world where we can collect home runs from players with moderate power, like we have the past couple seasons, that’s what I’m doing. But if we go back to something resembling the baseball from the early part of the 2010s, then we’re just not going to get as much power from these middle of road players. In that situation, when I need 3-4 players to build around my primary stack, I’m more interested in taking a secondary stack where we can look to collect Runs and RBI from a big inning or two that come through hits, rather than just chasing power everywhere.

This is very similar to what we saw last spring if you were up in the middle of the night playing KBO DFS. Remember the good ole Doosan Bears? Yeah you do! I am not for one second suggesting that we aren’t still chasing home runs in our DFS lineups, in fact we may need to chase home runs even more than we did in the past with the expensive players. Focus on the big power bats with a high hard-hit rate and fly ball distance. But again, if the DFS pricing matches the power potential, then we just aren’t as likely to be able to pick up free homers for $2,000. The 370-foot fly ball with average exit velocity is just more likely to be an easy out with a deader baseball. A line drive in the gap is a double in any ballpark with any baseball.


Whether your new to playing MLB DFS or, like all of us, have been busy with other things these past few months, I want to make sure we all start off on the right foot. These topics I’ve covered here, the small sample size stats and the changes to the baseball, are just secondary factors that are different this season. None of this changes the basic building blocks of analysis.

If you want to do more pre-season reading to get ready for Opening Day, I would again recommend these articles I wrote last spring:

Pitching Stats Analysis

Hitting Stats Analysis

But here’s the Cliff Notes of the Cliff Notes:

For Pitchers – Strikeouts, strikeouts, strikeouts. Sure, we care about the matchup and the ballpark and the hard hit rate and all sorts of other stuff. But as I’ve talked about incessantly in the past, there is nothing anywhere in the game of baseball that is more projectable than strikeouts. Going hand in hand with that is walk rate. The best pitchers in MLB have a high strikeout rate and a low walk rate. But for DFS, and tournaments in particular, I weigh strikeouts higher than anything. Plus, with talking about the new baseball, there are also reports that the grip is better for pitchers, which could help strikeout pitchers even more. As a point of reference, the league average strikeout rate has been around 23% the past two seasons, with the ace pitchers closer to a 30% strikeout rate.

For Hitters – Hit the ball hard and often. Batted ball variance is huge. But quite simply, the more balls a batter puts in play and the harder he hits them, the better he’s going to be. Generally, I put hard hit ability ahead of contact ability, although that could potentially start to even out depending on the baseballs. But again, when Miguel Sano hits the ball (which doesn’t happen a lot), it’s going to go a really long way, which is known from his hard hit rate. But since he strikes out 40% of the time, that doesn’t always do you a lot of good. What you want is Juan Soto. He hits the ball hard and he doesn’t strike out. Hit the ball hard, hit the ball often and good things happen. Good things = DFS points = $.

Images Credit: Imagn

About the Author

Dave Potts (CheeseIsGood)

One of the preeminent baseball minds in all of fantasy, Dave Potts (aka CheeseIsGood) has won contests at the highest levels of both season-long and DFS. He is a 2x winner of a $1,000,000 1st-place prize in DFS; having won the 2014 FanDuel baseball Live Final and following that up by taking down a DraftKings Milly Maker Tournament in 2015. In addition, he’s won the Main Event championship in the National Fantasy Baseball Championship and the NFBC Platinum League, which is the highest buy-in entry league. His consistent success in the NFBC tournaments earned him a prestigious spot in their Hall of Fame. Dave can also strum a mean guitar while carrying a tune, and if you’re lucky, you’ll see him do so on one of his MLB Crunch Time appearances. Follow Dave on Twitter – @DavePotts2