Drew Pomeranz and his trouble with the curve

Drew Pomeranz has gotten off to a poor start and his curveball is to blame

Featured image courtesy of Zimbio.com: (April 19, 2018 – Source: Jason O. Watson/Getty Images North America)

If you have been watching the Boston Red Sox closely, you have probably noticed Drew Pomeranz has not been very effective. To be fair, he has made just two starts, making his 2018 debut a little over a week ago against the Oakland Athletics. With that said, in those games he has pitched to the tune of an abysmal 7.27 ERA and 6.52 FIP in 8 and 2/3 innings.

His command has been erratic with a 4.15 BB/9 (walks per 9 innings) this season and the Rays participated in a Homerun Derby off him Friday night, ballooning his HR/9 (homeruns per 9 innings) to an unsustainable, but no less unsightly, 3.12. While he won’t be allowing three long balls every start, the command issues and the quality of contact being made against him are disconcerting.

In his first start versus of the season, the A’s posted a Hard% (percentage of hard contact) of 60.0% against him. This was the highest percentage of hard contact he has allowed in a start in over a year. In fact, he has made only one start in his entire career that featured a higher Hard%. It was a game against the Toronto Blue Jays on July 23, 2015 and the southpaw lasted just 1 and 2/3 innings with a 66.7 Hard%.

His next start against the Rays was better in the hard contact department, allowing 46.7% of balls put play to fall under that classification. In terms of Soft% (percentage of soft contact), however, 0.0% of the balls put in the play were labeled as such. Pomeranz faced 21 batters in the start and zero of them made weak contact. I don’t know whether to be impressed with the Rays’ hitters or aghast with the quality of contact he was surrendering. Either way, it was the second relatively rough start of the season for the 29-year-old.

It has been well-documented that Pom’s velocity has been down. In fact, in the month of April 2018, which is officially in the books, he averaged 89.37 mph on his four-seamer, per Brooks Baseball. This is slowest average monthly velocity in any month with the pitch in his entire career (he debuted in 2011). He has never dipped below 90 mph with the four-seamer, averaging 91.78 mph on it in 2017.

Additionally, it is not just his four-seamer’s velocity that is down. Check out this line graph, via Brooks Baseball:


On the X-axis, we have every year of Pom’s career and, on the Y-axis, we have the average velocity on each of his pitches. You most definitely could have figured that out yourself, but I have a self-imposed word count to adhere to, damnit.

Anyway, the velocity on the slider, four-seamer, sinker and cutter are all down, while the changeup velocity has actually increased. It makes sense that the other pitches are suffering velocity loss in unison with the four-seamer. I do, however, wonder if this is the byproduct of physical, diminished velocity across the board or if it is a conscious effort by Pomeranz to maintain the same velocity separation with his offering as he did in previous seasons. Putting it another way, if Pomeranz knows his four-seamer is not as fast, does he intentionally slow down his other pitches to play off the fastball and preserve the same velocity difference as in other successful years?

It’s a good question (wow, that was arrogant) but it’s impossible to determine. As such, I will leave that question to fade away into an unanswered oblivion, akin to the answer to “what is the meaning of life?”

Moving away from my weird, off-putting tangent, it appears Pomeranz’s pitch usage is all out of whack. If there’s anything you should know about his pitch usage and tendencies, it’s that he has a wonderful curveball (knuckle-curve) and he uses it almost as frequently as his four-seam fastball. The effectiveness of his curveball is very much intertwined with how well he pitches in a given game. Unfortunately, in the early going, he has been using his knuckle-curve noticeably less and, when he does throw it, the pitch is not nearly as effective. Here is another graph, courtesy of the wonderful Brooks baseball.

This graph shows the percentage of time Pomeranz has used his four-seam and curveball over his career. His other pitches are used a very paltry percentage of the time, and there are no significant usage changes with them, so I have omitted them from this graphic. It just makes it look cleaner and easier to understand. Good stuff.

Last season, Pomeranz hurled his renowned breaking ball 37.02% of the time. Despite seeing it quite frequently, hitters could only muster a weak .338 slugging percentage off it, hitting it on the ground 63.64% of the time per balls in plays. Batters also whiffed on the pitch 9.7% of the time they saw the curveball, contributing to the 7.0 pitch value (0 is average, 20 is extraordinary) it received on Fangraphs.

As you can glean from the graph, in 2018, though still incredibly early, Pomeranz’s curveball usage is down to 25.44%. If this usage percent maintains (which it will not) throughout the year, it would be the lowest yearly curveball percent since 2012 for Pom. I have to reiterate, here, though, that it is just two starts. Do not read too much into this. There was a three-start stretch last year (July 7th-July 19th) when the 29-year-old tossed under 25% curveballs in every game. If you followed Pomeranz last season, you know he turned out quite fine with a stellar 3.32 ERA over 173 and 2/3 innings.

Outside of the usage, however, the curveball’s effectiveness has not been the same. When it has been thrown, hitters have clobbered it for a .546 slugging percentage. It also is not generating the whiffs that it did in years past, seeing batters whiff on the pitch just 4.65% of the time. Meanwhile, the pitch value of the knuckle-curve currently reads -3.2 over at Fangraphs. At this point of the season, the predictive value of any of those numbers in the paragraph is negligible. They’re descriptive of what has happened, not predictive of what is going to happen.

Regardless, there are concerning, early trends with the curveball, the in-game effectiveness of the pitch notwithstanding. Check out the last of the triumvirate of graphs from Brooks Baseball. 

As mentioned in the beginning, his average curveball velocity is down fairly significantly. Velocity is something that stabilizes very quickly, as does pitch movement. Big Smooth, which is one of his nicknames according to Baseball Reference,  has always gotten a lot of vertical break on his knuckle-curve. It is an instrumental part of why the pitch has been so successful. With that said, in the month of April, it is getting more break than ever before at -10.28 inches.

Perhaps that is too much break? Are hitters able to recognize sooner because it has 1-2 extra inches of break? It’s entirely plausible.

An alternative explanation of the poor results could be that he is tipping his pitches, leading hitters to identify it more effectively. Actually, that is what some are speculating and Red Sox pitching coach Dana LeVangie will be looking out for signs of tipping in the pitcher’s next start. Here’s a quote from the Boston Herald. 

“I don’t know if he’s tipping or not,” said pitching coach Dana LeVangie. “But I’m going to watch to see if he his…There were some curious swings for me throughout the game that made me think about watching a little more video.”

While the tipping theory would explain a lot, as far as the curveball is concern, there seems to be a more logical answer. Simply put: Drew Pomeranz is not locating his curveball like he has in the past. Instead of staying down in the zone (where you want breaking balls to go), he has been throwing them higher in the zone(where you don’t want breaking balls to go). Below are different, equally fun graphics from Fangraphs that show where his curveballs have been concentrated in 2017 (good) and early 2018 (not so good).



In the 2017 graphic, we see a nice concentration of curveballs that are fairly low in the zone. Meanwhile, in 2018, we can conspicuously see they are all over the place, leaking way too high. Granted, there is another small sample size caveat, here. It’s much easier to have fluctuation in two starts than an entire season of work, hence, why his heatmap in 2018 looks like a giant, messy black hole with lava brimming out of it. Still, it appears Pomeranz has been radically inconsistent with the curveball and the heatmap reflects as such.

It is incredibly early in the 2018 season and it is hard to read too much into two appearances from Pomeranz. Still, there are some disconcerting things with his curveball right now. For one, the velocity is down on the offering, while it is getting more, and different, vertical movement than ever before. Lastly, the pitch has been landing all over, in and out of the zone. Ultimately, only time will tell if these early signs were predictive. Regardless, I’m comfortably asserting Drew Pomeranz’s 2018 success will live or die the effectiveness of the knuckle-curve.

We can hope he does not have too much trouble with the curve going forward.

Mic drop.



Patrick Green

Founder and owner of Red Sox Unfiltered. Communications major at UNCC.

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