RADIO
Jon Anderson takes a look at which hitters improved the most in 2021 as compared to their 2019 and 2020 numbers to find fantasy baseball draft sleepers and breakout candidates.
There are plenty of different ways for a hitter to improve at the plate. We see dozens of players every year who make huge improvements at the plate, and it's very important for fantasy managers to identify these hitters earlier than the field does.
Sometimes these improvements can be driven by luck, sometimes by a change in approach, and sometimes just an increase in skill. It is vital to be able to identify who improved because of luck and who really improved. Keeping a close eye on strikeout rate is a great way to get evidence about this.
Since the 2020 season was so short, I want to always reach back into 2019 as well when comparing 2021 to past data. For this analysis, I combined 2019 and 2020, found every qualified hitter's strikeout rate, and then compared them to their 2021 mark.
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Why Does It Matter?
The fantasy category that this makes the biggest difference on is batting average, which is featured in almost every fantasy league you will find. There are a handful of factors that go into batting average, but no input is more important than strikeout rate. If you put a ball in play, you have at least some chance of earning a hit from that. If the ball in play is a line drive, you have something like a 70% chance of getting a hit, and everything but a pop-up will give you a greater than 20% chance.
Let's quickly check on the relationship between these two variables. First, I grouped all hitter seasons from the last six years together by their strikeout rate while rounding that rate to the nearest 5%. I then took the average batting average from all those groups. Here are the results:
You see there that the batting average goes down as the strikeout rate goes up. I'm not making any waves here, this is inherently obvious, but I think it's interesting to see. You will be hard-pressed to find a guy that can hit .250 while striking out near 30% of the time. Conversely, it's tough to find a hitter with a 15% strikeout rate not giving you a .265 batting average or better.
I put together one of my famous interactive scatter plots here, showing each qualified hitter since 2015, plotting their K% and batting average together. You can hover over each dot to see who it represents.
You see the downward trend in the same way as we see in the first plot, meaning that as your strikeout rate rises, your batting average goes downward. There are some outliers here, notably Yoan Moncada's 2019 season where he hit .315 despite a 27.5% strikeout rate. On the flip side of that would be Kevin Newman in 2021; he hit just .226 on a really low 7.4% strikeout rate. Obviously one of those guys was hitting the ball harder and at the optimal trajectory way more often than the other, but neither of those results is something you are going to see hardly ever.
Okay, so now I'm made my point about the batting average. This goes beyond that into other categories as well, of course. Let's take a 600 plate appearance season and compare a 30% strikeout rate with a 25% strikeout rate. Ignoring walks, a 30% strikeout rate in 600 PA would result in 180 strikeouts and 420 balls put in play. At a 25% strikeout rate, that turns into 450 balls in play. That's 30 extra chances for hits, runs, homers, RBI, and steals. That can make quite a bit of difference.
Now, let's see who made the biggest improvements in 2021.
Biggest Improvements
Using just qualified hitters and fantasy-relevant hitters here, I prepared this table that shows every hitter that improved their strikeout rate by at least four points.
Brendan Rodgers is the top dog here, although that is mainly because of his 32.4% strikeout rate between 2019 and 2020, which came out of just 102 plate appearances, barely making the cut I used here. Chances are with 100 or so more PAs in those first two years, his strikeout rate would have come way down. But anyway, the 20.2% rate in 2021 was really, really strong (league average is around 25%), and that should help him post a really nice batting average this year in Coors Field.
The most exciting name on the list is probably Luis Robert, who we viewed as a free-swinging, high-risk player coming into 2021 because of his high strikeout rate. It is murky territory drafting guys with 30%+ strikeout rates just because of how bad that can hurt in batting average, but Robert made a huge improvement there in his 295 plate appearances in 2021.
Matt Olson is right there with Robert as a stud fantasy hitter that made a really surprising improvement in strikeouts last year. That 17.1% K% really is eye-popping when you consider the 39 homers he hit. Only Jose Ramirez and Vladimir Guerrero Jr. cleared 35 homers with a K% under 20%, really impressive stuff.
Lower K% with Maintained Power
One thing you will see quite often is the trade-off between power production and contact. One easy way to make more contact is to swing the bat with less velocity. Not only does this make the swing easier to control, but it also makes it so the barrel of the bat also stays in the hitting zone longer, giving it a higher probability of contacting the moving baseball. Because of this, some of the names above might be a bit misleading.
For example, Jorge Soler appears on the list, bringing his K% down from 28% to 23.6%. That's an improvement of 4.4 points, but it came with a reduced barrel rate as well (coming from 18.5% to 13.6%). Now, a 13.6% barrel rate is still really good, but you can see that he had to give up a few home runs in order to make more contact. The same was true for Gavin Lux, who brought the K% down to 22%, but his barrel rate dropped just as steeply down to a pretty pitiful mark of 3.9% in 2021.
The sweet spot here would be hitters who improved their K% while maintaining or increasing their barrel rates. Let's find them:
| Player | K% Change | Brl% Change |
| Max Muncy | -4.7% | +4.0% |
| Abraham Toro | -8.2% | +3.4% |
| Brendan Rodgers | -12.2% | +3.1% |
| Hunter Renfroe | -7.5% | +3.0% |
| Daulton Varsho | -7.2% | +2.9% |
| Bryan Reynolds | -4.9% | +2.8% |
| Kyle Tucker | -6.2% | +1.6% |
| Austin Riley | -6.0% | +1.3% |
| Lewis Brinson | -4.2% | +1.2% |
| Mitch Haniger | -4.2% | +1.2% |
| Teoscar Hernandez | -7.3% | +0.2% |
| Garrett Hampson | -5.0% | -0.2% |
| Pete Alonso | -6.4% | -0.2% |
| Tommy Edman | -5.1% | -0.4% |
| Juan Soto | -4.3% | -0.4% |
| Luis Robert | -11.5% | -0.5% |
| Carlos Correa | -4.8% | -0.5% |
| Matt Olson | -10.4% | -1.3% |
All things considered (draft cost included), the guys I am most interested in for fantasy this year from this list: Rodgers, Renfroe, Varsho, Riley, Hernandez, Alonso, Robert, Olson.
This is something that is super useful in-season as well. Don't overreact to a few weeks of data, but keep an eye on the strikeout rates throughout the year to see who is really crushing their career averages - it usually results in a much-improved fantasy line. Thanks for reading!
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