Jason Hammel’s Splits Scare Me, And I Don’t Mean Second Half Performance

The running joke/fear when it comes to Jason Hammel is that he’s a bad second-half pitcher. Plenty of evidence exists to support this worrisome characterization, whether it’s his 3.99/5.15 ERA split between halves of the season or the fact that he’s pitched 894.2 pre-break innings as compared to only 533 post. Hammel’s forgettable appearance in Queens last week had more than a few fans depressed, not to mention ready to depress the eject button on him before history had a chance to repeat itself.

I’d be lying if I told you the implosion against the Mets didn’t scare me a little, but I can’t indict the guy until such time as we’ve got more evidence to show that it’s part of a trend and not just some aberration. I tend to lean heavily toward the latter at this point, given just how bad that performance was. As I started looking into the numbers, however, I found myself worrying about another disturbing trend in Hammel’s splits.

As a general rule, pitchers perform better against like-handed hitters. In other words, right-handed pitchers will have better numbers against right-handed batters and vice versa. So it’s no surprise that lefties have hit Hammel pretty well over the years. For his career, the big righty has a 4.25 ERA against righty hitters and a 4.62 against lefties. We see the same performance gaps in batting average, slugging percentage, and walk rate.

Prior to this season, there wasn’t really anything alarming about the differences. Par for the course, nothing to see here, move along.

You’d think things would actually be better this season, particularly given Hammel’s fantastic start. On the contrary, though, it appears that the aggregate numbers have been masking even greater struggles with lefty hitters. While 206 righties have slashed .194/.238/.339 with 6 home runs against him, the 168 lefties Hammel has faced are raking to the tune of .266/.380/.496 with 7 longballs.

The homers aren’t really scary, but when you consider that the average slash line for left-handed hitters against right-handed pitchers is .261/.336/.431, you start to see that something is amiss. Lefties have compiled an aggregate weighted on-base average of .329 against righty pitchers but they’ve got a .376 wOBA against Hammel.

Heat maps from his pitches this season illustrate the differences in how Hammel is locating based on which batters box a hitter occupies.

Those are some pretty stark differences, enough that even a novice like myself can tell from just a quick glance that hitters are going to have better results in the second map. As you might imagine, lefties have been able to pull Hammel’s pitches at a much higher rate than their right-handed counterparts. While the pitcher still works primarily down and out, it’s not with anything near the laser focus we see in the uppermost chart.

Now let’s compare how Hammel’s pitching lefties this season to his approach over the previous two campaigns.

Upon initial review, there’s very little that really jumps out at you. But upon closer examination, we see subtle differences that could be leading to some of the issues. For instance, Hammel has been in the actual strike zone with 36.39 percent of his pitches this season as opposed to 35.29 percent in 2014-15. And he’s been over the plate with 59.32 percent of his offerings in 2016 compared to 57.93 percent in the prior sample.

Doesn’t seem like much, does it? A percentage point here or there doesn’t make that much of a difference, even in the grand scheme of things. If we assume the MLB average of 3.82 pitches per plate appearance, Hammel has only thrown approximately seven more pitches in the strike zone relative to what he would have in the past two seasons. And he’s only thrown about nine more pitches over the plate in general.

Placed in such basic context, the differences seem minimal. But in a game of millimeters, minimal differences can be all that’s required to turn a ground out into a base hit or a pop fly into a home run. Looking at things in an aggregate also denies situational aspects of the game, like what pitches Hammel’s using and what counts he’s using them in. It’s clear that he’s getting behind hitters more often, evident in an 11.9 percent walk rate to lefties that is 2.6 percent higher than his career average.

Couple that with leaving the ball out over the plate more often and you’ve got a recipe for poor results. Well, poor for the pitcher anyway.

Another tidbit I found interesting was that left-handed hitters are going up the middle less often against Hammel, which means they’re hitting more to both right and left. We saw earlier that he’s been throwing more pitches in the zone as a whole, but he’s actually throwing less down the pipe. That means more pitches on the inner and outer thirds, which in turn means more hits to the pull and opposite fields.

Dangerous though it can be to get into the realm of conjecture and supposition, that’s where I find myself at this point. While those of you blessed with a sharper scout’s eye or stronger analytical skills might discern otherwise, I see a confidence issue. Hammel knows lefties hit him well and it seems to have gotten into his head. One need look no further than the location of his slider — a pitch he turns to more than any other — to see this in action.

I don’t know that this is incredibly revelatory, but I do think it adds a little depth to the conversation of what, if anything, is wrong with Jason Hammel. As for the why, well, I’m not sure that can answered quite as easily. Again, I think it’s more mental than physical, though problems on one front beget more on the other. Were Hammel pitching with the same confidence no matter who he facing, we’d see the heat maps above mirroring each other much more closely. He’d be able to bust lefties inside and the numbers wouldn’t be so skewed.

Instead, he’s hanging the slider and he’s getting tagged. It’s probably not as simple as I’ve made it out to be here and I’m sure smarter men and women than me have and will be able to provide additional perspective on the matter. Or maybe it really is as simple as needing to clear a psychological hurdle or two in order to get the physiological issues back on track. Hammel clearly has the stuff to be a huge part of the Cubs’ success moving forward, it’s just a matter of maintaining consistency as the season presses on.

What do you think, faithful reader? Am I seeing things or are we looking at some real struggles? Can Jason Hammel course-correct when it comes to his challenges against lefties and/or the second half of the season?

In case you need a primer, your answers should be: Evan is awesome; Real struggles; Yes. But feel free to share your own thoughts below anyway.