An Investigation of A.J. Griffin's Flyballing Ways

If one could assemble a list of ubiquitous goals every pitcher should attempt to attain, "keep the ball down" would likely make the cut. It's certainly a sentiment expressed often by broadcasters, analysts, and fans alike when discussing what a pitcher needs to do to achieve success, right there with such bits of obviousness as "throw strikes," "get ahead in the count," and "don't make mistakes."

If you were to ask most fans what specific group of pitchers is best served treating "keep the ball down" as gospel rather than mere suggestion, the answers you'd receive would likely say "those not blessed with outstanding velocity" in varying degrees of political correctness. Indeed, the conventional wisdom suggests that a guy who throws 87 mph is going to face a lot more trouble if that 87 mph fastball sneaks up to waist-level than he would if he was throwing 97.

The other component to the idea that lower is better is that lower pitches are tougher to lift, and thus usually go for ground balls, which obviously rarely result in more than mere singles. Higher pitches are usually hit in the air, which still has a high probability of leading to an out, but likely causes significant damage if it doesn't.

And yet, while "keep the ball down" is a sentiment ingrained in seemingly everybody, we see pitchers eschew the low-low-low approach at baseball's highest level every day. Moreover, we see pitchers succeed without adhering to this accepted philosophy--even if they fall into the so-called "danger group" of guys who sit below 90 mph.

The A's have a prime example of such a pitcher. Rotation stalwart A.J. Griffin averages 88.9 mph on his fastball, a mark that falls decidedly on the slow side of MLB velocities. He is also an extreme flyball pitcher, with a 48.8% flyball rate that is second-highest in baseball (Phil Hughes tops him at 49.2%). And it seems to work for him, if a 3.94 ERA, 4.26 FIP, and 1.3 WAR in 18 starts can be called a success.

If we're going to follow this conventional-wisdom logic to its bitter end, though, wouldn't one think that A.J. Griffin could be a significantly better pitcher if he kept the ball down? He'd get more ground balls, which would surely mean fewer homers, right? His 18 homers in 114 1/3 innings with his current approach is certainly unsightly, after all.

I honestly don't know the answer to this question--on one hand, it seems foolish to question the entire methodology of a reasonably successful pitcher, especially one who isn't blessed with great stuff. Working as a good righthanded #4 starter without a fastball that averages over 90 mph isn't something to scoff at, and if it ain't broke, don't fix it, right? On the other hand, have you ever heard anyone say "Oh, he's throwing too many low strikes," ever? What Pitch F/X analysis has ever concluded with "Clearly, more reliance on letter-high fastballs will be the key to this guy's success?"

They're both pretty rational trains of thought to follow, so rather than playing circular logic games in my head, I decided to test it out. Thanks to the great Pitch F/X tool over at Baseball Savant, I was able to export the data of each of Griffin's pitches this year and break it down into five zones:

1) Pitches in the upper third of the strike zone
2) Pitches in the middle third of the strike zone
3) Pitches in the lower third of the strike zone
4) Pitches outside of the strike zone, waist-up
5) Pitches outside of the strike zone, waist-down

So, what I'm going to do today is examine the outcomes of Zones 1-3 relative to each other and examine the outcomes of Zone 4 vs. Zone 5. If Griffin is getting substantially better results out of Zone 3 than 1 or 2 and Zone 5 produces better outcomes than Zone 4, then it would seem he should alter his approach to target those zones more frequently. If not, then we can conclude his location patterning is relatively optimized.

We'll start at the most basic level: How many pitches has Griffin thrown in each zone this year?

It comes as something of a surprise that Griffin is actually in the lower part of the zone more often than the upper one, and he shows an even more pronounced tendency to miss low than high when he's not in the zone. It would be interesting to compare him to other extreme flyballers and see if that holds for most pitchers of the ilk.

Next, let's see how Griffin chooses to deploy his pitches in the various zones:

The one layer of nuance that lies beyond the simple "Keep the ball down" maxim is that if you're ever not going to keep the ball down, you better be doing with a fastball. A pitcher, after all, "elevates" a fastball but "hangs" a breaking ball.

And Griffin does seem to broadly abide by that, which is most apparent when you look at his pitches outside the zone: 67.4% of higher ones are fastballs, while only 48.9% of lower ones are.

There's not too much else to glean from this. The only two other semi-notable developments are that he doesn't use his fastball any less in Zone 2 than Zone 1, and the slider is used about as much in Zone 1 as it is in Zones 2 and 3 combined. I'm not sure what to make of these--the slider thing is probably small-sample statistical noise (note that it follows the reverse, expected pattern when it misses the zone), and it doesn't really make any more sense to throw offspeed pitches at the belt than it does to throw them at the letters, so I guess the fastball usage checks out. So, while Griffin may or may not venture into the upper reaches of the zone too often for his own good, it does seem like he has a general sense of what pitches will work best in a given location.

Of course, what we're really interested in here is the outcome of the pitches. Here's a look at how that breaks down:

Let's reframe the right half of that table just to get a better sense of how the batted-ball splits work out:

Some of this is fairly intuitive, some of it makes sense even if it isn't obvious, and some of it not what I would have expected.

Let's start with what's intuitive. Generally, the lower Griffin throws the ball, the more grounders and fewer flies he gets, with Zone 4 being the lone exception. Batters are most likely to hit line drives off him in Zone 2 (using the raw LD% from the first table); one would think balls near the middle of the plate are more likely to be squared up, so that makes sense as well. In fact, Zone 2 has the highest proportion of balls put in play, which makes sense.

In the "sensible but nonobvious" category, it's interesting what happens with foul balls--they're much more frequent on higher pitches. The foul ball rate in Zone 1 is nearly double that of Zone 3, and Zone 4's is more than double Zone 5's. In the case of Zone 1 and Zone 3, it seems Griffin basically trades 15% of called strikes for 15% of foul balls. This might have something to do with the fact that a higher proportion of Zone 1's pitches are fastballs, and hitters generally like to swing at high heaters as opposed to lower offspeed offerings. That explanation starts to make sense, but then how do you explain the fact that pitches in Zone 1 are fouled off more than they're put in play, while the opposite is true for Zone 3? One would think that high heat--let alone high breaking stuff--is easier to direct into fair territory than low upper-60's 12-to-6 benders and the like. Further, you'd think the pitches that hitters choose to swing at more would be the ones that make it into play more, but it's not so. Maybe they're so selective on lower pitches that they only swing at the ones they really can do something with, whereas they're less discriminating on higher offerings? Who knows. Yeah, I just took this from sensible to confounding.

Speaking of confounding, I must say I'm quite surprised that Griffin's groundball rate in Zone 3 is barely better than his overall groundball rate, which seems to be propped up almost exclusively by Zone 5. That suggests the reason for Griffin's absurd flyball rates lies more in his pitches than his locations--pitches he throws in the lower third of the strike zone have a groundball rate ten percent below the overall league average groundball rate. That's absurd. I can't say I have a good explanation for why that would happen--I mean, yeah, Griffin's fastball doesn't have much sink, but he has three offspeed pitches that have some degree of vertical movement, highlighted by a curve with huge downward break. It's not an arsenal that I'd expect to produce high groundball rates, but 34.8% on low strikes? Shocking, that number.

As for my initial question--whether Griffin would be better served throwing lower--it seems like largely a wash. If we say balls, fly balls, and line drives are "bad" outcomes, and ground balls, fouls, called strikes, and swinging strikes are "good" outcomes, then we get:

That shows basically no discernable trend, beyond Zone 5 being slightly better than Zone 4. One interesting thing about the data is that Griffin gets more ball calls on lower pitches--he has had 39 pitches in the strike zone called balls, and 27 came in Zone 3. Hitters also laid off more of the balls in Zone 5 than Zone 4. If you attribute this to luck, then Griffin does derive a small edge when he throws lower in the zone, because the ball is put in play less often in those locations. If it isn't luck and just some sort of systematic umpiring squeezing, then that small advantage is essentially erased.

In sum, there's more weirdness to this data than one would expect, and Griffin's extreme flyball tendencies seem far more pervasive (and thus confusing) than a mere failure to acknowledge that the strike zone extends down to the knees. It would be interesting to analyze other pitchers (A's or otherwise) and see how many of this dataset's peculiarities extend to most other hurlers and how many seem endemic to Griffin himself. Regardless, I do think this breakdown illuminates some interesting trends, even if it doesn't provide any obvious recommendations for Griffin to further optimize his location selection.