Michael Wacha St. Louis CardinalsZach Gifford | THE INTREPID STL

photo by @cardinalsgifs

Tonight, Michael Wacha takes the hill against New York Yankees opening day starter Masahiro Tanaka. Wacha looks to build on a strong season debut in which he allowed only one run over six innings to the Reds. Really, though, his strong start dates back to spring training, where he posted a 2.42 ERA and 3.26 FIP over 26 innings.

While health was the obvious theme for Michael Wacha this spring, his curveball kept coming up as well. Wacha’s breaking ball has never been a go-to pitch: for his career, he’s only thrown the curve about 10% of the time. When he has thrown it, it’s been slightly below average by wCB in every year except 2015. With that in mind, it was strange to hear St. Louis Cardinals manager Mike Matheny call the pitch a “weapon” at the end of spring training, per Rick Hummel of the St. Louis Post-Dispatch.

It’d also be strange to jump to conclusions after only one regular season start. Yet, that’s all we have data for thus far in 2017, so it’ll have to do. While the sample size is small, sometimes we can still gain valuable insights. For example, Joe Schwarz already noted that Michael Wacha flashed a new sinker in his first start, even though he only threw four of them.

Michael Wacha also threw five curveballs that game. One of them ended in a Zack Cozart triple toward Matt Adams that really should have been an out. Three others were taken for called strikes, and one more was taken for a ball. Nothing to see here, right?

Not so fast.

From 2015 to 2016, Michael Wacha averaged a spin rate of 2,073 rpm on his curve. That’s extremely low compared to the league average of 2,397 rpm since 2015. In fact, it ranks 56th out of 60 pitchers who have thrown at least 500 curves in that period.

That ranking becomes more relevant when considering the relationships between curveball effectiveness and spin rate. I’ve found fairly strong results between whiff rate (r=0.4464), ground ball rate (0.6435), exit velocity (-0.3452), and launch angle (-0.5622) all in favor of more curveball spin.

So, mark me as pleasantly surprised when I saw that his five curveballs from last Saturday averaged 2,324 rpm. While it’s still below average, it’s no longer bottom of the barrel. It represents a 251 rpm increase over his Statcast era average, approximately a 12% difference.

In fact, the lowest spin rate Wacha’s gotten on a curveball this season is 2,263 rpm. In the 565 curves he threw from 2015 and 2016, he only managed to generate that much spin on 47 of them (8.3%). A sudden jump that large probably isn’t just a product of small sample size or random chance.

It’s likely not just the result of better health, either. In April of 2015, Michael Wacha generated an average curveball spin rate of only 2,020 rpm on 35 pitches. In April of 2016, he averaged 2,175 rpm on 52 curveballs.

One of the key and most obvious benefits to increased spin is an increase in movement. Thus far, Michael Wacha is generating about 1.5 more inches of horizontal movement and nearly three more inches of vertical movement compared to his curveball career averages. For the first time in his career, he has a pitch with as much glove-side movement as his changeup has armside movement.

While the changeup and curveball don’t look much alike coming out of the hand, it’s still helpful for a pitcher to get equal but opposite movement on a pair of pitches. Furthermore, Michael Wacha could use a consistent third pitch to go with his fastball and changeup. If that third pitch was a curveball, he could find himself working at three very different and distinct velocities with a mid-90 mph fastball, a mid-80 mph changeup, and a mid-70 mph curve. With that repertoire, he’d have the requisite tools to really mess with hitters’ timing.

There are a few possible sources for the increase in spin and its implications. For one, he might just be stronger overall. In that case, we’d expect to the spin rate to increase on all of his pitches. While his spin rate is also up on the cutter, the spin on his fourseamer and changeup are no different from the last two years. Thus, it looks like he’s just doing something differently on the two glove-side breaking pitches, rather than an increase from overall strength.

Maybe, then, he’s changed how he throws the curveball, either through a different grip of different arm action. For what it’s worth, he’s averaging the lowest vertical release point on his breaking ball by a few inches.

There’s also a chance that the increased spin is just variation due to a tiny sample. It could be due to tracking errors or park effects. Maybe these first five curveballs don’t mean anything.

But maybe they do. Maybe Michael Wacha has a curveball that really is a new weapon. If that is the case, it would go a long way toward keeping Wacha established in the St. Louis Cardinals rotation.