Jan 14, 20183 min read

Curveball plays vital role in completing Michael Wacha's repertoire

Updated: Jan 15, 2018

Admittedly, one of the more interesting discoveries while looking back through last season's statistics was just how much value Michael Wacha provided to the 2017 St. Louis Cardinals. Posting an fWAR (FanGraphs WAR) of 3.2, only Carlos Martinez (3.3) provided more pitching value to the club. Even then, Martinez barely nipped Wacha despite having ~40 more innings pitched (205.0 versus 165.2) to accrue a higher total. Sure, some will scoff at Wacha's average innings per start (5.52) or his difficulty the second and third times through the order (I will have more on this in a future post), but bottom line, Wacha provided a great deal of value to the club.

Ever since Wacha's burst onto the scene in 2013, he's been primarily characterized as a fastball-changeup pitcher. I was excited about what appeared to be a sinker introduction during his 2017 debut start, but upon further review, those pitches have since been recalibrated as a mere outlier (and subsequently reclassified as a fourseamer). The cutter has served as his third pitch since his debut season, but at an average velocity of 91.25 MPH, a fourth pitch, at a discernibly different velocity would clearly serve him well long-term. Fortunately, last season, that fourth pitch, averaging 77.10 MPH (aka a "discernibly different velocity"), was the curveball, and boy, it was effective.

In 2017, Wacha transformed what began as nothing more than a work in progress into a downright lethal weapon. It possessed the ninth most vertical movement and provided the 10th most value among MLB starting pitchers, according to Pitch Info. For those interested in individual results, the curve led to whiffs on 30% of swings and yielded a minuscule batting average of .167. Sure, the sample size is still small (only 306 curves thrown in 2017; or 11.38% of his total pitches thrown), but it has certainly come a noticeably long way for the 6'6" right-hander.

Other than results, what actually changed with the curveball last season? Is 2017's success repeatable? As with most pitch analysis, let's start with location (courtesy of BaseballSavant.com):

While the change isn't necessarily drastic, there exists a demonstrable shift in the core down and away (from righties) and down and in (to lefties). This can be attributed to conscious change in approach (I was unable to ask him about this, individually) or a direct result of slightly more horizontal and vertical movement in 2017. The expected wOBA on the curve in the new core? .225, as opposed to .276 only one deviation higher in the zone. Shift that curve toward the middle, and the xwOBA climbs even higher to .287.

When asked about the curve during his Q&A at the Winter Warmup, Wacha responded, "It'd had never been a pitch that I could count on in certain times throughout the game. Over the season, it was one that I started to trust more and more, and it started becoming an out pitch for me towards the end of the season. So, it's something I'll definitely be continuing with and hopefully becoming something in my repertoire, for sure."

Thus, when considering the bump in movement, better location, and increased confidence, the curveball is primed to be that desired "third" pitch for Wacha. I say "third" instead of "fourth," because of the vulnerability and frankly, inconsistency of the cutter. Heck, the changeup hasn't even been the same as what we saw in 2013, so the curveball may be on the path as the primary out pitch off his fastball.

As you'd expect, this post would not be complete without the inclusion of visuals, courtesy of @cardinalsgifs.