MLB Best Curveballs: The Best Curveballs of 2018
In today’s game where seemingly everyone throws hard, it takes more than just a good fastball to make the cut in the big leagues. These pitchers exemplify that and take it to the next level with the best curveballs of 2018.
On this week’s edition of the best pitches of 2018 we are going to take a look at the starting pitchers with the best curveballs in the game. As with the best four-seam fastballs piece from last week, we won’t simply be looking for the best individual curveball thrown but the larger body of work that the pitchers put together with the curve. We will still only be looking at starting pitchers with this exercise and to qualify, the pitcher must have thrown at least 250 curveballs on the season. These rankings are comprehensive based on several different aspects of the pitch. I won’t simply be ranking curveballs based on break, but also several other metrics deemed to be valuable to produce a productive curveball:
Movement
Movement is inherently one of the most important aspects of any pitch. This is especially true when discussing any type of breaking pitch. The point of the curveball is to confuse the batter by throwing something that moves very differently from the generic, straight fastball. Good horizontal and vertical movement are critical for having a good curveball but they are not the only factors that produce a quality bender.
Spin Rate
Spin rate is a newer concept at least to the general baseball audience, but it has been proven to be an important factor to pitch performance. A high-spin breaking ball will have harder and later movement than a pitch with lower spin. The later the ball begins to move the less time the hitter has to recognize the pitch and adjust, therefore having a curveball with a high spin rate will typically be more effective than a loopy curveball with less spin.
Whiff Rate
Swing and miss rate or “whiff rate” is the percentage of times that a batter swings at a pitch and misses. This is one of the single most important pitching statistics as it is a statistical illustration of how nasty the pitch is to the hitter. Ground balls are great but no damage can be done on a pitch that is never hit. Whiff rate is especially important when analyzing curveball quality as a curveball is often used as a strikeout pitch. It is thrown out of the zone to induce a chase.
xwOBA
Expected Weighted On Base Average for my money is the ultimate per plate appearance pitching stat. It takes into account strike outs, walks and balls in play based on their expected outcomes. Using expected outcomes is much better than actual outcomes because there are so many random and lucky things that can happen on a batted ball. Giving the pitcher credit for these events that are out of his control is simply the wrong way to look at it. Looking at xwOBA allowed by pitch type will give us an idea of how well the pitcher was able to produce the kinds of batted balls that typically result in outs.
Expected Weighted On Base Average as well as whiff rate are also good statistical illustrations of command. If the pitcher is able to execute and spot his pitches properly he is more likely to get swings and misses or induce weak contact. At this point there is not a great way to quantify command so this is as good a way as any to look at it.
Without further ado, I present the top curveballs by starting pitchers in 2018: