Boston Red Sox outfielder Mookie Betts add more power, aggressiveness at plate

A year ago, Mookie Betts was one of the more divisive young talents in baseball. Mostly overlooked by scouts due to his diminutive size and lack of power -- he was a fifth-round pick by the Red Sox in the 2011 draft -- Betts ended up crushing minor-league pitching in 2013 and 2014 to put himself on the prospect map, though opinions about his future still varied pretty widely. Over at FanGraphs, we were pretty big fans based on his overall value skillset, but our enthusiasm was met with a lot of skepticism over the perceived lack of upside from a small contact hitter who generated a lot of value by drawing walks against inferior pitching. 

And those concerns were somewhat legitimate. When I first wrote about Betts on JABO a year ago -- suggesting that the Red Sox keep him rather than get tempted into dealing him for a frontline starting pitcher -- I developed a list of offensive comparisons based on his swing and contact rates. There were some good names on that list, including Joe Mauer and Matt Carpenter. There was also the Tony Gwynn that doesn't make for an optimistic comparison, along with Craig Counsell, Daric Barton and Sam Fuld. The low swing rate/high contact types almost universally didn't hit for power, and guys Betts' size often end up being defensive-oriented players who try to slap enough singles and steal enough bases to avoid being an offensive hole. 

Well, with his first full season nearly in the books, I think it's safe to say that Betts is not a slap hitter. On Tuesday night, he launched his 16th home run of the season, and perhaps more impressively, hit his 42nd double. Add in the eight triples, and Betts now has 66 extra-base hits on the year, the same number of extra-base hits as Nelson Cruz (who is tied for the major-league lead in home runs) and Jose Abreu, and four more than Cubs slugging rookie Kris Bryant, who was the consensus top prospect in baseball in large part because of his prodigious power. And that puts Betts five extra-base hits ahead of Andrew McCutchen, who became the popular comparison this spring, when Betts was torching the Grapefruit League in spring training. 

In the piece I wrote about the McCutchen comparisons, I noted that a similar kind of power spike was unlikely for Betts, given how rare it was for McCutchen to enter the league as a contact-oriented line drive hitter before giving up some contact in order to drive the ball with more regularity. The only other recent hitters who had made similar contact-for-power trade-offs after getting to the big leagues were Robinson Cano and Carlos Gomez; there just weren't a lot of guys who had come up as contact hitters and then developed into guys who hit for a good amount of power. 

It's still too early to be putting Betts in McCutchen's class as a hitter, but in 2015, he's done quite a bit to answer questions about how well his minor-league power would translate to the big leagues. Interestingly, however, the trade-off that he has made isn't really the same one McCutchen has made. Instead of making less contact, it looks like Bettes has traded in some walks to try to hit for more power instead. 

In his debut last year, Betts offered at a very low rate of pitches, swinging at just 35.9% of the balls he was thrown; this year, that swing rate is up to 40.4%. Interestingly, the majority of the increase has come on pitches out of the strike zone. The table below shows the distribution of the change in his swing and contact rates.

Betts' Swing and Contact Rates

When it comes to pitches in the strike zone, Betts' swing rate has only ticked up slightly, from 51% to 53%. It's the out-of-zone swing rate that has spiked, going from 19% to 27%, or the lowest mark in baseball to something just a little below the league average. Specifically, he's swinging much more often on pitches away; 18% of pitches off the plate outside but still within the height range of the strike zone, compared to 6% in the same area last year. But that's not really where his uptick in power has come from. Below, I've included power heat maps for both 2014 and 2015. 

As you can see, Betts didn't hit for any power on the outer-third of the plate (or further outside, where his swing rate increase is most dramatic) last year. And despite an uptick in power on pitches middle-away but still in the zone, he's not really hitting for a lot of power on the outer-third (or further) this year either. The primary change is that he's hitting for power on pitches directly down the middle, which he oddly didn't do a year ago. Perhaps the two changes are related, and Betts' has unlocked some of his middle-of-the-plate power by gearing up to swing more frequently on pitches away; he did say that he was being too passive at times last year. 

"€œ[Big-league] pitchers are just around the zone more. I feel like you have to swing a little more. You can'€™t go up there taking,"€ Betts told The Boston Globe. "€œI kind of learned last year that you can'€™t go up there taking. You'€™ve got to be ready to swing it. That'€™s how [Derek] Jeter got 3,000 hits. He wasn'€™t up there taking. That'€™s kind of why my approach is a little more aggressive than it used to be, which is all right. I feel like it works both ways -- it cuts down on strikeouts and it may cut down on walks, but that'€™s OK. I'€™ll take [walks] when they come, like today. I feel like I didn'€™t really get a good pitch to hit, especially with guys on second and third, and ended up working a walk from there

"€œI think [the more aggressive approach] just kind of just developed over last year, especially against [big-league] pitchers. They're kind of in the zone with everything. I feel like if you go up there taking, you'€™ll be 0-2 in the blink of an eye," he added. "€œIt'€™s not something that I think about. It'€™s just something that'€™s naturally been an adjustment, the same way I always say -- I feel like I just make natural adjustments."€

There's no question Betts has been more aggressive this year, but perhaps the most interesting part of the evolution is that Betts has upped his power while retaining his in-zone selectivity. If the increase in out-of-zone swings isn't the cause for his increase in middle-middle power -- and it probably isn't, given that plenty of guys can crush the pitches in the middle of the plate without also needing to chase pitches away -- then it seems possible that Betts might be able to tap into the best part of his approach from each of his two seasons in the majors. If he can figure out how to keep hitting for power at this level while also reducing his chase rate back toward something close to last year's mark, Betts might very well be able to draw walks and hit for power. 

And if he can do that, then those Andrew McCutchen comparisons won't look silly at all.