The Case for Slowing It Down

I would imagine that one of the most jarring pitches for a major league batter to face is an extremely slow breaking pitch. Conventional wisdom might suggest the opposite — something like triple-digit heat. But at least a batter knows to expect high-end velocity when he steps to the plate against a given pitcher. A pitch under 70 mph, on the other hand, is rare enough that it can freeze you. Not familiar with the types of pitches I am talking about? Here are a select few.

Since 2015 (i.e., the Statcast era), just 0.3% of all pitches thrown in MLB have been under 70 mph; pitchers today generally live in velocity bands from 10 to 30 mph higher. Being able to slow the ball down to such an extreme degree without tipping off the batter to what is coming is not trivial, and being able to drop these pitches in for strikes takes practice. Taking time in a throwing session to lob lollipops into the strike zone probably seems foolish to many pitchers, especially if they can just throw 95 mph instead.

I understand the roadblocks to throwing slow looping curveballs. But whenever I see a pitcher throw them, they often seem to disarm the batter, who usually doesn’t swing. In that scenario, the worst-case result is often a ball, and if the pitcher can locate the pitch, he can nab a strike with little resistance. And as fastball velocity continues to increase across the league both this year and in seasons past, pitchers are increasingly leaning on breaking balls and offspeed pitches to fool hitters who are geared up for heat. With that in mind, a super-slow curveball could be a useful weapon.

Is my intuition correct? To test it, I decided to pull up every pitch since pitch tracking began in 2008, via Baseball Savant, and filtered for those that traveled less than 70 mph and were labeled as a curveball or eephus. The tricky part here was that a lot of those pitches were thrown by position players, which complicates my thesis because (surprise) position players are bad at pitching. To counter that, I downloaded all the team rosters since 2008 from Retrosheet, then selected all the pitchers in the dataset and filtered the pitch data with the condition that the player throwing the pitch appeared in the list from Retrosheet. Here are the players who threw the most pitches that met the criteria since 2008:

And here is a similar table but for players in the Statcast era:

The first table is an excellent list for remembering some guys. The more recent list consists of players that the contemporary baseball fan is more familiar with. Greinke’s exploits with these pitches are well documented. Bassitt, Mills, Ryu, and Corbin are known for using guile and deception to get through innings, often to great effect. Visibly absent from either list are strikeout monsters like Jacob deGrom, Gerrit Cole, and Shane Bieber, who already put away over a third of opposing hitters via the strikeout and, with their ability to throw 95-plus, don’t need to mix looping curves into their arsenals. Focusing on such a pitch would be a waste of time and energy for pitchers who are already dominant.

So when do these slow breakers get used? As it turns out, they’re most often the first pitch of a plate appearance, and to great effect:

The average CSW% for all pitches is about 28%, so 38% on first pitches is very good. These pitches are rarely swung at, though, so the swinging-strike rate is low, as is the first-pitch strike rate. They also yield few swings in general. That flips in two-strike counts, likely because the batter is willing to swing at anything near the zone, as opposed to being behind in the count, when hitters are probably gearing up for a fastball. It makes sense, then, that slow breakers show up most often when they’re most likely to catch a hitter by surprise — starting an at-bat or when a pitcher has fallen behind — and that, by extension, that’s when they’re most effective in terms of strike rate.

Back to the list of players who threw these pitches the most in the Statcast era. In general, those pitchers were relatively successful (remember that the average CSW% is 28%), particularly when it came to getting swings and misses versus the overall numbers above:

It’s worth noting that most if not all the players listed in this piece didn’t or don’t have the luxury of reaching back for 95. Veterans like Greinke or Wainwright have lost their velocity over time, forcing them to get creative and comfortable with softer breaking balls to offset their diminished fastballs. Pitchers like Wright and Dickey, meanwhile, never had that velocity to begin with; their trade was slow stuff by default. But regardless of how they came to throwing at the speed limit, those pitches were or have been an asset (albeit a small one) in their arsenals.

I do think it is fair to recognize the pitfalls of leaning so heavily into this type of pitch. Hitters rarely swing at them, so any pitch outside of the strike zone will likely result in a ball. Batters have had trouble putting these pitches into play with any authority, to the tune of an average exit velocity of 84.4 mph since 2015, but the count leverage lost from throwing balls adds up over the course of the season when you look at run expectancy. And as I already outlined above, there are difficulties in throwing pitches this slow. Hang a 65-mph curveball, and it’s going to get hit a lot harder and farther than a 95-mph fastball. Maintaining deception by not altering the pitching motion is obviously imperative, too, as is locating the pitch for a strike.

But if those prerequisites are met, slow breakers should continue to be a useful way to steal the occasional strike throughout the course of a game and season, at least until batters make an adjustment. And I imagine that such an adjustment would be difficult, as siting on a 70-mph pitch probably isn’t a good idea for a hitter. I will be interested to see if these pitches become if not commonplace then at least used more often, and if hitters can combat them to make them less tenable than they seem at the moment.