Jason, Get A Popup!

For a player who finished last season with relatively modest results, we here at Wrigleyville have spilled a fair bit of ink over Jason Hammel. It can be difficult to pinpoint exactly how to feel about his stint with the Cubs, and I believe it is this curiosity which leads to our continued efforts to dive into the tumultuous nature of his tenure.

My friend and esteemed writer Eno Sarris recently wrote a piece that caused me to reflect upon Mr. Hammel yet again. We have believed that the single most accurate predictor of in-season pitcher performance is strikeout percentage minus walk percentage, but Sarris builds upon this insight by adding popups induced—as sure of an out as a strikeout—to gain further insight into a given pitcher’s performance. The top of the list includes all of the familiar names you’d expect, but coming in at number 29 is none other than Jason Hammel.

This immediately struck me as odd, as he is known as a pitcher that works with a two- and four-seam fastball down in the strike zone; those are pitches that are fundamentally designed to keep hitters from hitting the ball with lift. After parsing the data a bit more, I realized that Hammel’s inclusion was purely due to an elite strikeout minus walk-percentage, and had nothing to do with his ability to induce popups. In fact, his 1.5 percent popup-rate ranked dead last of the top-50 pitchers in the KPU-BB% stat Eno was assessing. If you expand the list to include all qualifying pitchers, he checks in at 131st out of 142.

Hammel is proof that an elite strikeout-minus-walk percentage is not enough to guarantee success, the same way the top of this list illustrates that an upper-echelon popup-rate also does not necessarily predict positive outcomes. However, there is plenty of evidence to suggest that combining the two metrics (KPU-BB%) is an excellent indicator of premium results.

So, we’ve established that he could possibly benefit from inducing a few more easy chances for his infield, as adding this ability would complement his elite K/BB marks effectively, thus positively affecting his bottom-line stats as well. But this begs the question, has he ever achieved this in the past? Beyond that, does he have the ability to adapt in such a manner, without harming the rest of his profile?  Let’s dig in deeply to try and answer these riddles.

The first part of solving this equation is understanding where Hammel attacks the zone, as this is a clear indicator of the propensity to force popups. Let’s take a look at Hammel’s profile before 2015, first:

That’s a pretty balanced profile. Lots of pitches up, and a whole lot of pitches down in the zone. Now let’s look at his profile in 2015, split into two halves.

2015: April-July 1st                                                                                2015: July 2nd-October 1st

It takes a moment of digestion to comprehend the difference between the two profiles, but after studying it I believe we’re on to something. During his successful first half effort, Hammel attacked hitters low and away effectively, but remained balanced in continuing to work the upper-half of the zone, and especially the critical upper inner-third of the zone. In the second half, he strayed from the balance, choosing instead to pound the lower outer-half with more regularity. Despite the slight differences when you look at the chart visually, the resultant effect is an over 10 percent cumulative spread between lower-outer and upper-inner quadrants. But did it effect his ability to induce popups? You’d better bet your bottom dollar it did:

2015: April-July 1st                                                                                2015: July 2nd-October 1st

Now, adding the additional easy chances for outs is one (very important) thing, but I believe Hammel straying from using the inner upper-half also had the ancillary effect of hitters preying on his insistence of attacking the bottom of the zone. The hitter’s lack of having to pay respect to the inner-upper areas made him more vulnerable to any pitch left in the middle and lower parts of the zone, and they feasted on these offerings as a result.

2015: April-July 1st                                                                                2015: July 2nd-October 1st

While reviewing this, compare these charts to his historic results, and you can get a better sense of why controlling the upper inner-half holds such importance:

When he hits his spot low-and-away, hitters simply cannot handle him. However, the same could be said of his pitches up-and-in. What this means is that when he’s utilizing both quadrants of the zone, he works with similar effectiveness in each. However, when he abandons the upper-inner quadrant, his overall effectiveness wanes right along with it.

Though the results pretty clearly show that he changed the way he approached the zone, I don’t believe this was intentional. Instead, I believe he unconsciously trended toward his biggest strength—inducing grounders from the bottom of the zone—as he came back from injury and possibly felt the need to compensate for diminished velocity:


Month Fourseam Sinker Change Slider Curve
4/15 93.50 93.34 86.01 83.68 76.75
5/15 93.07 93.28 85.71 83.68 77.37
6/15 93.10 92.97 85.80 85.21 77.41


Month Fourseam Sinker Change Slider Curve
7/15 92.56 92.44 84.90 84.75 76.69
8/15 92.96 92.77 85.48 86.02 77.83
9/15 92.70 92.94 85.44 86.46 77.08
10/15 92.06 92.31 84.89 85.98 76.28

Both his fastball and sinker suffered dips in velocity post injury, possibly lending credibility to the assertion that some of his struggles came from his desire to compensate for having lesser stuff. Hammel is on record attributing his second-half struggles to fatigue, but moving forward it is critical that even if he does feel that his velocity has diminished as the season wears on, he must continue to utilize more than just the lower-outer quadrant as discussed. His ability to find this balance likely has more impact on his effectiveness than his velocity does.

None of this it suggest Hammel should fundamentally change his approach. His success is and always will be predicated upon inducing groundballs, and maintaining a strong strikeout minus walk-percentage. However, I believe the above information clearly points out that utilizing the upper-inner quadrants of the zone—and thus inducing more popups—follows closely behind as a catalyst for his success.

Lead photo courtesy Jerry Lai—USA Today Sports.

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4 comments on “Jason, Get A Popup!”


I would imagine for attacking right-handed hitters in the upper inner third, Hammel would most likely be using his fastball.

Has Hammel seen a similar drop in velocity, in particular fastball velocity, in his second half splits in prior years (non-injured years), given the general drop in second half numbers he has produced?

Isaac Bennett

Yes, most likely you’re talking either fastball or front-door curve, but mostly the one would be dropped.

You really have to go all of the way back to 2009 to find a season in which he pitched a fairly even amount of games between first and second half. No question he has had some late-season durability issues. Definitely something to keep an eye on, as the Cubs depth could come in handy. To answer your question, he didn’t see a velocity dip in 2009, no.|SI|FC|CU|SL|CS|KN|CH|FS|SB&time=month&minmax=ci&var=mph&s_type=2&startDate=04/01/2009&endDate=10/01/2009

You did such a Great job on this article do you mind printing off your best article you think you’ve done I wanna use you and your webpage for my presentation in Career Cruising. You can just give it to me on Sunday if you can. Thanks so much!!!!! just email me on the email above.

Isaac Bennett

Thanks, Austin. Yes, I can bring a copy for you.

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