Fluke Watch: Jason Hammel

Jason Hammel has had a pretty mediocre career. He’s had good peripherals in 2009-2010, but aside from those two years, he’s been the very definition of unimpressive. This is made even worse by the fact that Hammel’s had an above-average BABIP for his career (in particular, during 2009-2010, making his “improvements” seem less impressive). Of course, he has pitched the last three years in Colorado (though he had better numbers in 2010 at Coors than away).

But this year, Hammel has seemingly broken out. He’s currently running an ERA/FIP/xFIP line of 1.97/2.82/2.95—a line that you’d expect to see from an ace, not Jason Hammel. His strikeout rate is up to a level that would be a career high and his walk rate has dropped back in line with his 2009-2010 levels. And then there’s the groundball rate, which has risen from 43 percent—below average—to an amazing rate of over 60 percent. Where did this come from? Is it a real improvement?

Hammel’s pitches

Before this year, Hammel used a standard arsenal of four pitches: a four-seam fastball, a change-up, a slider, and a curveball. He relied heavily on his fastball (57 percent of pitches against right-handed hitters, 63 percent against lefties), with the slider being used as a clear secondary pitch against right-handers and the change-up/curveball being used as the secondary pitches against lefties.

None of these pitches were partticularly impressive. Hammel’s fastball had good velocity (averaging 92.9 mph last year), but unspectacular movement. Hammel’s slider also had decent velocity (you may be noticing a theme here) at around 84.3 mph, but is nothing special in terms of movement.

This year, Hammels has added a new pitch: a two-seam fastball. The pitch is sometimes labeled as a “sinker”—in fact Harry Pavlidis briefly mentioned it on Tuesday for THT HERE. Yet this label is sort of misleading: The pitch doesn’t have very much sinking action at all. The pitch IS clearly different than the four-seamer that had previously been Hammel”s mainstay—it tails in on right-handed batters around eight inches on average as compared to the five inches of tail on the four-seamer. But while the pitch is nice, there’s no reason—movement-wise, at least—that the pitch should make Hammels dominant or that it should be a heavy groundball pitch.

Now Hammel’s pitches have increased in velocity overall by about half a mile per hour, which should not be understated. But there nothing about the pitches them selves that should explain his results.

Hammel’s results

Hammel’s two-seam fastball has a groundball rate of 77 percent against right-handed hitters. Once again, this is a pitch without much natural sinking action, relying mainly on velocity and location to get ground balls. Except he’s not using the two-seamer to frequently hit good groundball locations—he’s not getting low and away locations to these batters.

Hammel has gotten ground balls against lefties with his four-seam fastball (seven of 10 balls in play on the ground) and both of his breaking pitches (five of five balls in play on the ground). But there’s no reason for this to have occurred. Hammels hasn’t changed how he pitches much in terms of location or usage in such a way that would cause this. He hasn’t gotten ground balls with his two-seam fastball or change-up, a fact which isn’t surprising as two-seamers have a clear platoon effect on ground balls and his doesn’t have huge sinking action.

All in all, Hammel’s ground ball rate reads quite strongly as a fluke, with regression seemingly on the way. Hammel’s increased velocity (if he can keep it up) and the addition of the two-seamer should result in him getting more ground balls this year than last, but not a huge amount more. Optimistically, he should get around 50 percent ground balls if his improvements are real—still a solid rate, but not elite.

Of course, there’s another reason why Hammels has such good peripherals this year: His strikeout rate is at a career high. Is this also a fluke? Well, perhaps not completely. Hammel has changed his approach to pitching slightly. In addition to the two-seamer, Hammel has increased his slider usage on two-strike counts, which makes sense as it’s his best strikeout pitch.

Similarly, the two-seam fastball—while not a good strikeout pitch against righties—has so far been a good pitch at getting whiffs against left-handed batters. And if you look at how Hammel has used the pitch to left-handers, you can sort of believe this to be real: Hammel uses the pitch against lefties to near exclusively pound the outside part of the plate. (More than 80 percent of his two-seamers have been on the outside part of the plate to lefties, with most of the other 20 percent being in the middle of the plate). This is an area of the plate that should in theory get whiffs from lefties.

But there are some warning signs about his whiff rate, too. Much of his increased ability to get strikeouts has come from his four-seam fastball, which has above a 10 percent swinging strike rates against both lefties and righties. A typical fastball has a swinging strike rate of around five percent, so this is pretty insane. And yet, Hammel isn’t using his four-seamer much differently from last year and certainly not in a way that would explain such a super swinging strike rate.

So where do I see Hammel’s swinging strike rate going by the end of the year? Probably around his career rate of 6.34 percent, or maybe around seven. This would be an improvement over Hammel’s 2011 performance, but that performance seems more of a fluke than anything else in his career.

One last note: It’s very possible that some of Hammel’s non-two-seam improvements are caused simply by the availability of the two-seamer. In other words, the fact that a batter now has to worry about the two-seamer could—probably does—make his other pitches better to an extent, at least in the short run before batters adapt. But the improvements to Hammel’s other pitches’ results are just too large for me to accept that it can be from this effect.

Conclusion

Hammel’s addition of a two-seam fastball has improved his pitch repertoire, and will help him be a better pitcher this year. But his performance so far seems unsustainable.

His two-seamer doesn’t seem to be good enough in movement/speed/location to improve his results—particularly his groundball results—as much as they’ve looked so far. I wouldn’t call his improvement a “mirage”—he has changed something—but it is likely flukey and regresssion is very likely. If you have Hammels and someone is looking for pitching, he seems like a very good candidate to sell high.