The Evolution of Javy Baez’s Pitch Recognition and Swing As Shown By Heat Maps

I could go on and on writing about Javy Baez and how good I think he can be. In that, I’m not alone. The blogscape is chock full of articles about his exploits and his potential, though the focus has shifted quite a bit over the past few years. What began as awestruck admiration for his violent swing morphed into dumbstruck respect for his athleticism and baseball IQ. As such, the shiny object that originally captured everyone’s attention has now become an afterthought.

So does that mean the monster swing is gone? Well, yes and no. As he’s matured, Baez has learned when to unleash the beast and when to keep it caged. He’s becoming a more disciplined hitter and is learning how to take what pitchers give him. When he first came up, you basically had to hold your breath and hope the pitcher made a mistake and hung a slider. After spending most of 2015 back in AAA, however, we saw a selective eye throughout September and the postseason.

The hitter we’re seeing in 2016 seems to be a hybrid of sorts, willing to go outside the zone but with something other than murderous intent. Where the big leg kick and long stroke once left him unable to recognize and reach many pitches, Baez now employs a smaller timing step and shorter swing that allows him to shoot outside pitches to the opposite field or just put balls in play to advance runners.

The samples sizes are admittedly small, but below are looks at the pitches Baez saw and swung out in his time with the Cubs in 2014, ’15, and ’16. Come on, let’s check ’em out.


What really jumps out here is that we’ve got only one bright red square and four bright blues floating in a sea of purple. Those indigo parallelograms represent swing rates between 32 and 63 percent, which indicates a decided lack of discernment. Baez was swinging too often at bad pitches and not often enough at good ones, a sure sign that his recognition was pretty awful.

As we jump to 2015, the changes are stark:


It’s admittedly difficult to make any real pronouncements from only a month or so of data, but it’s pretty obvious we’re looking at a different hitter, philosophically speaking. Just look at the red through the middle of the zone and the blue around it. We can see above that seven of the nine squares inside the strike zone boast swing rates of 64 percent or greater. The same could be said for only one during the previous season (with one more at 63 percent).

While Baez actually swung at roughly the same percentage of pitches outside the zone year over year (39.3 vs 39.5), his swings at pitches inside the zone jumped from 58.7 to 68.3 percent. That boosted his overall swing rate from 46.8 to 51.5 percent, and the results were appreciably better.

Those upward trends have continued this season:


That’s a lot of red, man. The overall swing rate is up nearly three percent, again lifted by a Z-swing (in the zone) percentage that has jumped to 77.8 percent. Baez is swinging at a few more pitches outside the zone in 2016 too, but what’s truly remarkable is what he’s doing with those swings. Over his first two MLB stints, Baez made contact with only 43.6 percent of the pitches he swung at outside the zone. This season, however, that number has jumped to 65.9 percent.

Contact rate on pitches in the zone has dropped a bit, but the overall rate is up. Strikeouts are way down, every component of his slash line is way up, and Baez’s wRC+ of 129 is an indicator of just how good his offensive production has been. Javy has posted 0.6 WAR in only 43 plate appearances, which is already better than his total from last season (0.5) in 80 PA’s.

Honestly not a whole lot more insight to provide here that you probably don’t already know. I’ve just really enjoyed seeing Javy mature into a legitimate hitter instead of a swinger, a transformation vaguely reminiscent of what we saw with Jake Arrieta after coming to Chicago from the Orioles. I’m not saying Baez will make a similar quantum leap forward next year, but I’m not saying he won’t either.

While actually realizing his full potential is a long shot, Javier Baez has the tools to be all kinds of insanely special. For now, though, I’m content to revel in the fact that he’s becoming a really good baseball player and a more well-rounded hitter.

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