Curves with sub-2000 RPM spin rates

[Enscheff]

We have talked to death the fact that Anderson supposedly has a horrid 1700 RPM spin rate on his curve, and how that doesn't quite match up with reports that the pitch is average. We expect to see him debut sometime this season, and when he does we will finally get actual Statcast data for ourselves. Until then, we can take a look at the movement produced by other MLB pitchers with spin rates below 2000 RPM.

The movement grades for Curves is roughly (from a few years ago when I compiled this data):

Grade X Z
80 9.6 -11.0
70 7.8 -8.5
60 6.1 -6.4
50 4.3 -4.4
40 2.6 -2.3
30 0.8 -0.3
20 0.0 0.0

The problem is, there are no MLB pitchers who throw a Curve with a spin rate of 1700 RPM...that horrid mark is reserved for position players who pitch in blow outs. The hope is that value is wrong, and Anderson's true spin rate is closer to the 1900-2000 RPM range representing the bare minimum for MLB pitchers.

There were 7 pitchers in 2019 who threw 25+ Curves with an average spin rate under 2000 RPM. Here are their grades for movement on those pitches:

Kolby Allard 1883 RPM = -2.8" xMov (Grade 40), -5.9" zMov (Grade 55)
Nick Margevicius 1939 RPM = -4.1" xMov (Grade 50), -7.9" zMov (Grade 65)
Tom Eshelman 1944 RPM = 2.5" xMov (Grade 40), -5.3" zMov (Grade 55)
Drew Smyly 1950 RPM = 2.3" xMov (Grade 40), -2.4" zMov (Grade 40)
Blaine Hardy 1952 RPM = -3.4" xMov (Grade 45), -9.6" zMov (Grade 75)
Zach Plesac 1955 RPM = 4.1" xMov (Grade 50), -7.0" zMov (Grade 60+)
Patrick Corbin 1989 RPM = -2.0 xMov (Grade 40), -1.9" zMov (Grade 40)

So if we assume there is simply no way Anderson is a professional pitcher who can't muster ~1900 RPM on a Curve, there are some encouraging signs here. All these breaking balls are at least usable, and some like Margevicius and Hardy are very good.

I suppose it all banks on whether that 1700 value is really 1900...