Pitchers are often cited for their elite ability to command their pitches and miss bats. This requires a combination of pitch execution (both location and quality) as well as the pitch’s velocity and movement. From a scouting perspective, each pitch in a pitcher’s arsenal is graded on the 20-80 scale where anything between 50 and 65 is typically graded as a plus pitch and anything over 65 is a plus-plus. Since the slider is the most often used breaking pitch by today’s professional pitchers, we wanted to investigate the best sliders from the MLB using Statcast data and award the “Best Slider of 2019”. To do this, we’re going to look at hitters performance against sliders thrown from each pitcher in the MLB from 2019 using swing-and-miss rate, strike rate, and weighted on base average (wOBA) as key metrics.
Contact rate
Getting strikeouts is all about missing bats. The higher quality of a breaking pitch, the more bats it will miss. One of my favorite pitches to watch was Francisco Rodriguez’s sliders. It had such violent movement right as it got to the plate and was nearly unhittable.
To calculate a hitter’s contact rate, we must count the number of pitches thrown, pitches swung at, and pitches put into play or fouled away. For the purpose of this evaluation, we’ll divide the number of “swing and misses” by the total number of swings to calculate the contact rate. This essentially ignores balls and called strikes. Here’s the top ten for pitchers who threw at least 50 sliders in 2019.
| Pitcher | Sliders Thrown | Swinging Strikes Induced | Swing and Miss Rate (% of all sliders) | Sliders for Strikes | Swing and Miss Rate (% of sliders-strikes only) |
|---|---|---|---|---|---|
| Liam Hendriks | 284 | 82 | 0.288732 | 153 | 0.535948 |
| Kyle Gibson | 574 | 156 | 0.271777 | 302 | 0.516556 |
| Patrick Corbin | 1224 | 338 | 0.276144 | 658 | 0.513678 |
| Blake Snell | 127 | 29 | 0.228346 | 57 | 0.508772 |
| Max Scherzer | 573 | 152 | 0.265271 | 314 | 0.484076 |
| Michael Lorenzen | 140 | 29 | 0.207143 | 62 | 0.467742 |
| Mike Clevinger | 532 | 111 | 0.208647 | 240 | 0.4625 |
| Dylan Bundy | 632 | 141 | 0.223101 | 305 | 0.462295 |
| Felix Pena | 619 | 140 | 0.226171 | 305 | 0.459016 |
| Luis Castillo | 606 | 118 | 0.194719 | 263 | 0.448669 |
There is a pretty clear top tier of pitchers who can induce a swing-and-miss, with Liam Hendriks leading the pack. By reputation, Patrick Corbin has one of the nastiest sliders in the game. From a volume standpoint, he stands out with a whopping 1224 sliders thrown in 2019.
wOBA
Weighted on-base average, or wOBA, is a modern statistic used to account for total offensive output for a hitter. In addition to strikeouts, many pitchers rely on inducing soft contact and groundballs to get hitter outs. We ran our analysis for wOBA against sliders thrown in 2019 and as we did in the previous section, presented a table of the top 10 (or lowest 10) wOBA against. It’s worth noting that Hyun-Jin Ryu has a very impressive wOBA against of zero! He only threw 7 sliders according to Statcast in 2019, so it’s a very small sample size and we’re skeptical whether or not those pitches were really sliders and just miscategorized. At any rate, we’ve included the data, but Ryu can’t possibly wear the 2019 slider crown having thrown only 7.
| Pitcher | wOBA Against |
|---|---|
| Hyun-Jin Ryu | 0 |
| Liam Hendriks | 0.154819 |
| Justin Verlander | 0.171683 |
| Max Scherzer | 0.173529 |
| Sonny Gray | 0.188542 |
| Marcus Stroman | 0.200395 |
| Mike Soroka | 0.204248 |
| Frankie Montas | 0.204717 |
| Jakob Junis | 0.209073 |
| Patrick Corbin | 0.209404 |
Finer Statcast data
The beauty of the Statcast/Trackman era in baseball is the bounty of information recorded during every single game. Each pitch has data about the location of the pitch (both release and crossing the plate), horizontal and vertical movement, and speed (among other things). The slider is associated with more side-to-side (i.e. horizontal) than up-and-down (vertical) movement. A look at the more detailed location data from Statcast shows there is a correlation between the magnitude of the movement of the slider and the wOBA against. The table below shows the top 10 pitchers for total movement (horizontal plus vertical). An interesting name here is Trevor Bauer, whose attempt to manufacture the perfect slider is chronicled in the excellent book “The MVP Machine” by Ben Lindbergh of the Ringer. His success in creating movement with the pitch is undeniable.
| Pitcher | Total Movement (Feet) | Horizontal Movement (Feet) | Vertical Movement (Feet) |
|---|---|---|---|
| Elieser Hernandez | 1.90665 | 0.887119 | 1.01954 |
| Trevor Bauer | 1.83951 | 1.58707 | 0.252447 |
| Brad Peacock | 1.79214 | 1.15331 | 0.638829 |
| Sonny Gray | 1.7014 | 1.32613 | 0.375273 |
| Yu Darvish | 1.6445 | 1.39354 | 0.250958 |
| Mike Clevinger | 1.61618 | 1.40054 | 0.215635 |
| Trent Thornton | 1.60877 | 0.914254 | 0.694512 |
| Chris Sale | 1.52735 | 1.16912 | 0.358231 |
| Jakob Junis | 1.45526 | 1.22136 | 0.233899 |
| Max Fried | 1.40128 | 1.05646 | 0.344827 |
What pitch evaluation would be complete without discussing velocity and spin rate? Spin rate is indicative of swing-and-miss for fastballs, and we would expect to see that for other pitches as well, but comparing our leaderboards for swing-and-miss rate with spin rate (below), there are no pitcher’s who land in the top 10 for both. We do, however, see names of some of the elite MLB arms including Walker Buehler and Mike Soroka. When we plot the relationship of spin rate to wOBA, it’s clear there is a similar relationship as there is with total movement.
| Pitcher | Spin Rate | Velocity |
|---|---|---|
| Trent Thornton | 3088.98 | 80.4545 |
| Sonny Gray | 2868.46 | 84.6507 |
| Walker Buehler | 2867.26 | 86.8154 |
| Marcus Stroman | 2837.78 | 85.7126 |
| Mike Soroka | 2775.7 | 83.1768 |
| Brad Peacock | 2751.42 | 81.2828 |
| Trevor Bauer | 2739.8 | 79.6075 |
| Mike Minor | 2736.84 | 86.3714 |
| Carlos Carrasco | 2729.48 | 84.7371 |
| Yu Darvish | 2724.89 | 82.4273 |
And the best slider is…
There is a lot of competition for the best slider in baseball, and we were able to touch on a few of the charateristics of a lights-out slider. Liam Hendricks, closer for the Oakland Athletics, uses his slider in dominating fashion, resulting in a miniscule wOBA against of 0.155 and a swing-and-miss rate of 28.9% leading all of MLB in both categories. But, to get to those heights while also shouldering the load as a starter, Patrick Corbin gets our crown of “Best Slider of 2019”. He’s a bit shy of the number put up by Hendricks, but he did so at a volume of 202.0 innings pitched. Congrats Mr. Corbin (on the World Series win as well) and good luck defending your title in 2020.