Author: Jordi Parry (Weinberg ’22)

In the last few years, MLB pitching has changed enormously.  We’ve seen a stark decrease in the percent of innings thrown by starting pitchers, and a much higher number of hard-throwing pitchers, particularly relievers, have entered the league this decade.  However, not every pitcher is blessed with the ability to dial it up to triple digits.  Despite the league-wide increase in velocity, there are still a number of pitchers who can’t dial it up past 90 MPH on their fastballs but have carved out rotation spots in the MLB.  One would assume that these pitchers have found specific tendencies to be the most effective when compensating for their low fastball velocities, such as walking fewer batters or throwing more off-speed pitches. With this in mind, it’s time to look at some of the underlying numbers to figure out just how soft-throwing starting pitchers can succeed in a league that increasingly focuses on fastball velocity.  To try to get a sense of what makes for a successful soft-tosser, I grouped together 15 pitchers who threw at least 2,000 pitches in 2018 and had an average 4-seam fastball velocity below 90 MPH. While there are plenty more pitchers whose fastballs wouldn’t exactly be labeled as heaters, I identified this group as most relevant to answer the question.

Pitcher	4-Seamer
LeBlanc, Wade	86.2
Hendricks, Kyle	87.3
Yarbrough, Ryan	88.2
Estrada, Marco	88.5
Leake, Mike	89.1
Godley, Zack	89.2
Colon, Bartolo	89.3
Fiers, Mike	89.4
Shields, James	89.5
Greinke, Zack	89.5
Hill, Rich	89.5
Hernandez, Felix	89.6
Keuchel, Dallas	89.8
Chacin, Jhoulys	89.9
Teheran, Julio	89.9

Next, I thought about some of the stereotypes surrounding these kinds of pitchers.  From my time following the MLB and the biases I’ve found myself and fellow fans hold, I’d guess that most fans think of pitchers with low velocity as old control artists who throw a lot of offspeed pitches and don’t strike many guys out. While these assumptions do hold true to a certain extent for this group, it’s not as if all fifteen of these pitchers are late-career Greg Madduxes.  The average age of the group in 2018 was 32.13, which is above the league average.

I plotted the pitchers’ numbers in four different categories against their ERAs from 2018, in an attempt to identify which metrics correlated most with actual run prevention. The four numbers that I used were walk percentage (BB%), strikeout percentage (K%), average spin on fastball, and the percentage of their pitches that were fastballs or sinkers (sinkers were added in because some of these guys hardly ever throw real 4-seam fastballs – they are really sinkerballers, with their most prominent non-breaking ball pitch being their sinker).  Below is the graphed data (for reference, league average BB% is 8.5%, K% is 22.3%, and fastball/sinker % is 55%).

Looking at the relationships between these metrics and ERA, the clearest takeaway is that these pitchers aren’t so different from the rest of the league. The simplest path to success is to strike a lot of hitters out.  The pitchers within this group that gave up fewer runs were those who struck out more batters, with Zack Godley being the only real exception. This is interesting, as none of these pitchers give up particularly hard contact, so it would have been expected that there would be much less of a relationship between K% and ERA.  The next most significant factor is walk percentage, as, outside of Bartolo Colon and Mike Leake, the control artists in the group gave up significantly fewer runs than those who walked more batters. Despite the fact that these pitchers were surprisingly all over the board when compared to the league as a whole, fastball spin rate seems to have little effect on run prevention.  From Wade LeBlanc to Rich Hill, it appears that starters can find ways to get outs with low velocity no matter where their fastball spin falls on the spectrum. Finally, we have our most surprising result: fastball/sinker percentage does not seem to correlate to ERA. Given that these pitchers throw their primary pitches much slower than their peers, one would expect that a successful strategy would be to mix in off-speed pitches at a higher rate than the rest of league, but this doesn’t seem to be the case.  Guys like Kyle Hendricks actually throw fastballs at a higher rate than league average despite their low velocity and still find ways to perform.

In analyzing this set of starters, they look much less different from the rest of the league than one would have expected.  Control (walk percentage) is less of a factor than one would think, given the increased difficulty of striking batters out with slower fastballs.  Instead, these pitchers are still all over the board in the types of pitches they throw and how often they walk batters, but their strikeout rates are tied heavily to their run prevention.  It appears that the best way to keep up with their harder throwing peers is still to strike hitters out, no matter the speed on their fastballs.

Email jordanparry2022@u.northwestern.edu.