Kevin Siegrist and the importance of adding a curveball to his repertoire

Earlier this spring, MLB.com's Jenifer Langosch reported that St. Louis Cardinals late-inning relief pitcher Kevin Siegrist was adding a curveball to his repertoire after learning to focus on the desired pitch shape from "curve master" Adam Wainwright and picking up a comfortable grip from fellow lefty Tyler Lyons. Unfortunately, to my knowledge at least, we have not yet been provided with any updates on the progress of the pitch. Despite the absence of updates, the addition of, at the very least, an average curveball projects to be a critical contribution to the long-term success of Siegrist, versus left-handed and right-handed hitters.

2015 PitchF/x Basics (via BrooksBaseball.net)

Remember: Regarding horizontal movement in left-handed pitchers, a negative value means glove-side movement, whereas a positive value means arm-side movement.

At present, Siegrist's repertoire contains two (maybe three) pitches: a fourseamer, a changeup, and a reportedly "mostly phased out" slider (see Langosch's article linked to above and the frequency in which he used the pitch in the table as well). The natural movement of his two main pitches (fourseamer and changeup) is down and in to left-handed hitters (versus down and away to right-handed hitters). Admittedly, it may currently stand as an unsubstantiated myth that many left-handed hitters (not named Bryce Harper) "feast on" pitches down and in (this location is often classified as their "sweet spot" or "wheelhouse"), but it is still worth noting considering the natural movement of Siegrist's fourseamer and changeup.

Now, as long-time VEB community member brackenthebox pointed out in the comments section of my last Siegrist article, "Siegrist isn't even halfway to what [FanGraphs] calls the stabilization point for pitcher platoon splits. Based purely on his MLB stats, he's probably at least neutral if not better against LHB. He shouldn't be used as a situiatonal lefty because he's too good for that role, but I also don't think we should be worried to see him facing lefties." Because of brackenthebox's comment, I will no longer press forward with the possible presence of a "reverse split" with Siegrist just yet, not until we have a larger sample size to deal with at least. However, as stated in the paragraph above, the current makings of Siegrist's repertoire has a natural movement often more suitable to success against right-handed hitters (i.e. pitches breaking down and away, leading to weak or sometimes zero contact).

Thus, this is where we arrive at the importance of a curveball for Siegrist's long-term success. Right now, especially if the slider becomes fully "phased out," Siegrist simply does not possess a pitch that breaks away from left-handed hitters. Francisco Liriano, one of the best left-handed starting pitchers in the game, enjoys much of his success against left-handed hitters by snapping off wipe-out sliders, particularly with two strikes in the count. With Siegrist's current repertoire, the 26-year-old lefty is limited to placing a backdoor changeup on the outside corner (of note, he threw a grand total of five changeups to LHHs last season), fooling the hitter by changing speeds (with his slider most likely, a pitch he threw 87 times), or attempting to blow the hitter away with a mid-90's fourseamer (a pitch he used 385 times).

One must understand that the curveball is still very much a work in progress. It is not a pitch than can be mastered in an offseason plus seven weeks of spring training. Even when fully developed, it will not be nearly as effective as Liriano's slider, and frankly, that is okay, I was just using Liriano as an example earlier, not a comparison. The mere presence of a pitch with glove-side movement will expand the toolbox Siegrist uses to attack hitters, particularly with two strikes. And with more pitches to choose from, especially pitches that move in opposite directions horizontally, hitting against Siegrist will be even more difficult than it already has been in his two-plus year MLB career (calculated service time via Baseball-Reference: 2.116).

Finally, let's hope this early-spring development turns into something that is actually implemented during the regular season, unlike last spring when we were told (by Jenifer Langosch as well) that Lance Lynn was working on a "filthy" changeup, a pitch he ended up using only 3.11% of the time during the regular season. Manager Mike Matheny weighed in on Siegrist's spring curveball tinkering in Langosch's article as well:

"Terrific. The changeup still looks good, but the curveball is a wipe-out, strikeout pitch. It's just adding to the complexity of the approach for the at-bat."

A "wipe-out, strikeout pitch" is a useful weapon for left-handed pitchers trying to put away left-handed hitters, just ask Anthony Rizzo (from back in 2013).