Mookie Betts and Pull Power

Mookie Betts hit a pair of home runs against the Athletics on Tuesday, which hopefully for the Red Sox means that their star player’s power slump is over. Entering last Friday’s game, Betts had not homered in more than a month. Then, he hit this Fenway special.

And then, four days later, two more. But even with the recent barrage, Betts’ total of 21 home runs is on a trajectory to fall well short of the 31 he hit in his breakout 2016 season, and I can’t help but wonder if that Pesky Pole shot might be the key to understanding what has happened to his power. If you split up the field into thirds, then that Friday home run was his first to the opposite field all season and his fifth to the opposite field and center field combined. Last season, he had just four home runs that weren’t pulled. It turns out, that is a really low number. In fact, among the 37 players who hit 30 home runs and had 500 plate appearances, it was the lowest.

Fewest Not Pulled HR, 2016, 30+ HR and 500+ PA
Player Pulled Not Pulled Total
Mookie Betts 27 4 31
Curtis Granderson 24 6 30
Brian Dozier 36 6 42
Carlos Santana 27 7 34
Nolan Arenado 34 7 41
Albert Pujols 24 7 31

On the opposite end of the spectrum, the players with the most not-pulled home runs included Khris and Chris Davis, Chris Carter, Miguel Cabrera, and Mark Trumbo. It’s not perfect, but it visually looks like a player’s opposite-field power correlates to the sustainability of his home run total. And, frankly, that makes sense. It takes more strength to hit the ball out to the non-pull side; you can’t fake your way to double digit home runs to the opposite field.

I wanted to confirm that was a real trend, so I pulled player-seasons since 2002 where a player had 20 or more home runs. Then, I compared his home run total that season to his total the next season, assuming he reached 500 plate appearances in both. Those results suggest that players with fewer opposite-field home runs are likely to decrease their home run totals more than players with more opposite-field home runs, but the trend seems to exist more at the highest end of the spectrum where the Davises live. Put differently, Brian Dozier may not be any safer than Betts.

Year-to-Year HR Changes by Not Pulled Rate
Not Pulled Rate Sample Size Change in HR
Upper Third 261 -2.3
Middle Third 257 -3.2
Bottom Third 257 -3.0
20+ HR in Year 1, 500+ PA in Both Years

The top-four in not-pulled home runs this season are Khris Davis again, Giancarlo Stanton, Aaron Judge, and Joey Votto. They are the only four players with more than 20. Given their reputations, it’s not too helpful to tell you that their power is on the safer side. However, there are a handful of more-surprising 25-plus home run hitters who exceed the 45 percent not-pulled rate threshold that represents the upper tier. They are Corey Dickerson (57.7 percent), Ryan Zimmerman (54.9 percent), Justin Smoak (48.6 percent), and Adam Duvall (48.4 percent).

Betts falls short of that 25-home run threshold. Otherwise, he would have made the bottom five of not-pulled home runs, again. Of the players who did make the cut, several scare me for their 2018 power prospects.

Fewest Not Pulled HR, 2017, 25+ HR and 500+ PA
Player Pulled Not Pulled Total
Rougned Odor 25 4 28
Francisco Lindor 26 6 30
Jose Ramirez 21 6 26
Adam Jones 20 7 26
Mike Moustakas 30 7 36

Rougned Odor is going to come close to matching his total of 33 home runs from 2016—he’s at 28 with a few weeks to play. However, Odor has seen his total of extra-base hits drop precipitously, and his total of not-pulled home runs has fallen from 9 in 2016 to 4 this season. Maybe an injury can neatly explain his power outage and overall batting decline, but for a player whose only plus fantasy contribution is his home run total, his pull-only power is alarming.

Francisco Lindor is the player that looks the most like last season’s Mookie Betts. His 30 home runs this year double his previous career high, and he is not much bigger than Betts at 5’11 and 190 lbs. Lindor may be my favorite player to watch, but I think a 20-20 season is much more likely for him in 2018 than another 30-15 season.

Mike Moustakas doesn’t share Betts’ and Lindor’s youth, but he has had a similar power spike. His 36 dingers this season are 14 more than his previous best, and he actually has a moderately-long career to compare to. Moustakas is a dead-pull hitter. He’s never hit even a quarter of his home runs to left and center field. Don’t bet on a repeat power season.

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Scott Spratt is a fantasy sports writer for FanGraphs and Pro Football Focus. He is a Sloan Sports Conference Research Paper Competition and FSWA award winner. Feel free to ask him questions on Twitter – @Scott_Spratt

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“It’s not perfect, but it visually looks like a player’s opposite-field power correlates to the sustainability of his home run total.” That may be true in general, but as always players are individual snowflakes, and this must be approached with caution.

Take the Betts example. You’re looking for whether power comes and goes, but that isn’t the case with Betts. Rather, he simply hasn’t hit nearly as well this year, especially lately, and his power is connected to his hitting overall. If anything, 21 HRs despite a .262 BA suggests that his power is for real, and just tied to his overall hitting quality. If he hits .300+ in a given year, we should now have confidence that it would include 30+ HRs.

You look right that opposite field power is likely tied to HR consistency, but what does that really tell us? We know a Chris Davis type will hit his HRs no matter the quality of his season, but of course the performance of such hitters as a whole is still tied strongly to other, non-HR areas too.