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Revisiting the Cardinals’ spin rate data

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Now that MLB is checking pitchers, what do the numbers have to say?

MLB: St. Louis Cardinals at Detroit Tigers Raj Mehta-USA TODAY Sports

We’re now three weeks into MLB’s new enforcement policy regarding pitchers’ use of foreign substances. Of course, these developments are at least partially the result of Mike Shildt forcing the league’s hand with his press conference following Giovanny Gallegos Hatgate.

“Is our house 100% clean? I certainly hope so,” Shildt said in the aforementioned presser. “Am I creating more of an opportunity—because I just spoke to our pitchers—am I creating more awareness to our group? Potentially.”

I think the working assumption among Cardinals fans was that St. Louis’ pitching staff had to be at least relatively ‘clean’ for Shildt to go public with his remarks like he did. While we can’t arrive at definitive conclusions, analyzing changes in spin rate data from before/after June 21, the day pitcher inspections began, provides valuable pieces of information. Evaluating pitchers (especially as the trade deadline nears) is already a complex task; determining the potential effects of sticky stuff adds yet another layer.

With that in mind, let’s hone in on the Cardinals. J.P. Hill previously explored year-to-year trends in spin rate, and we can now begin to supplement that data by seeing what changes have occurred within 2021 under the enforcement guidelines. I included pitchers who threw at least five of a specific pitch type both before and after June 21st, which prompts an obligatory small sample size disclaimer. Another reminder: a decrease in spin rate in and of itself doesn’t prove much. To give the graphs and data table below a bit more context, Eno Sarris and Brittany Ghiroli wrote at the Athletic last month that “one standard deviation of change within a season for a single pitcher is 115 revolutions per minute.” In addition to individual metrics, you’ll also find the average spin rates for Cardinals in the sample as well as the overall MLB numbers for that pitch type.

Cardinals Spin Rate Data Table

Pitch Type Player Before Spin Rate After Spin Rate Spin Rate Change Before Pitches After Pitches
Pitch Type Player Before Spin Rate After Spin Rate Spin Rate Change Before Pitches After Pitches
4-Seam Fastball MLB Average 2307 2228 -79 N/A N/A
4-Seam Fastball STL Sample Average 2258 2207 -51 N/A N/A
4-Seam Fastball Reyes, Alex 2468 2302 -166 218 52
4-Seam Fastball Oviedo, Johan 2312 2194 -118 307 190
4-Seam Fastball Martínez, Carlos 2063 1975 -88 304 46
4-Seam Fastball Woodford, Jake 2198 2113 -85 117 11
4-Seam Fastball Gallegos, Giovanny 2359 2282 -77 259 84
4-Seam Fastball Kim, Kwang Hyun 2157 2088 -69 371 140
4-Seam Fastball Wainwright, Adam 2239 2174 -65 147 31
4-Seam Fastball Miller, Andrew 2042 2012 -30 44 9
4-Seam Fastball LeBlanc, Wade 2041 2026 -15 6 37
4-Seam Fastball Helsley, Ryan 2522 2519 -3 289 65
4-Seam Fastball Cabrera, Génesis 2258 2296 38 240 86
4-Seam Fastball Gant, John 2432 2499 67 131 29
Changeup MLB Average 1776 1711 -65 N/A N/A
Changeup STL Sample Average 1698 1693 -5 N/A N/A
Changeup Reyes, Alex 1529 1431 -98 25 13
Changeup Oviedo, Johan 1889 1810 -79 53 33
Changeup Martínez, Carlos 1858 1800 -58 143 29
Changeup Kim, Kwang Hyun 1644 1587 -57 91 38
Changeup Cabrera, Génesis 1771 1737 -34 86 31
Changeup Gant, John 1481 1486 5 241 37
Changeup Fernández, Junior 1956 1980 24 68 32
Changeup LeBlanc, Wade 1423 1535 112 12 55
Changeup Wainwright, Adam 1731 1873 142 73 10
Curveball MLB Average 2540 2472 -68 N/A N/A
Curveball STL Sample Average 2462 2406 -56 N/A N/A
Curveball Reyes, Alex 2850 2669 -181 68 13
Curveball Woodford, Jake 2485 2326 -159 64 15
Curveball Oviedo, Johan 2481 2369 -112 71 37
Curveball Wainwright, Adam 2840 2802 -38 461 103
Curveball Helsley, Ryan 2505 2475 -30 42 6
Curveball Kim, Kwang Hyun 2152 2123 -29 108 19
Curveball Martínez, Carlos 1961 1944 -17 5 9
Curveball Cabrera, Génesis 2412 2431 19 145 35
Curveball Gant, John 2469 2512 43 90 11
Cutter MLB Average 2409 2327 -82 N/A N/A
Cutter STL Sample Average 2328 2289 -39 N/A N/A
Cutter Martínez, Carlos 2201 2044 -157 220 54
Cutter Wainwright, Adam 2417 2375 -42 314 85
Cutter Helsley, Ryan 2454 2419 -35 157 54
Cutter Gant, John 2574 2578 4 79 36
Cutter LeBlanc, Wade 1994 2031 37 13 86
Sinker MLB Average 2151 2096 -55 N/A N/A
Sinker STL Sample Average 2125 2084 -40 N/A N/A
Sinker Reyes, Alex 2366 2202 -164 118 24
Sinker Elledge, Seth 2291 2173 -118 133 20
Sinker Martínez, Carlos 1972 1868 -104 132 44
Sinker Woodford, Jake 2012 1940 -72 127 17
Sinker Wainwright, Adam 2248 2193 -55 351 69
Sinker Miller, Andrew 1822 1810 -12 25 23
Sinker Gant, John 2380 2373 -7 432 68
Sinker Cabrera, Génesis 2193 2204 11 84 27
Sinker LeBlanc, Wade 1815 1861 46 7 65
Sinker Fernández, Junior 2146 2220 74 96 43
Slider MLB Average 2452 2384 -68 N/A N/A
Slider STL Sample Average 2374 2277 -97 N/A N/A
Slider Woodford, Jake 2459 2287 -172 101 12
Slider Reyes, Alex 2711 2554 -157 152 27
Slider Gallegos, Giovanny 2495 2345 -150 247 53
Slider Elledge, Seth 2397 2264 -133 56 10
Slider Martínez, Carlos 2076 1945 -131 255 36
Slider Oviedo, Johan 2566 2489 -77 147 71
Slider Kim, Kwang Hyun 2136 2092 -44 273 149
Slider Miller, Andrew 2492 2480 -12 164 68
Slider Fernández, Junior 2038 2038 0 47 21

I don’t know about you, but my first reaction when combing through the data was yikes, Alex Reyes. His 2021 peripherals were already concerning (3.50 FIP, 4.42 xFIP, 4.45 DRA) and a recent drop-off in spin rate doesn’t inspire confidence either. His velocity doesn’t appear to have changed significantly during the same timeframe. Curiously enough, if we dive deeper into the small sample size pool, Reyes’ FIP (3.80 to 2.32) and xFIP (4.57 to 3.81) have actually improved since June 21st, led by a much lower walk rate (20.6% to 8.6%) to compensate for a reduced strikeout rate (32.6% to 22.9%).

Other Cardinals with noteworthy spin rate declines (for navigation ease, I’d reccomend using the search bar at the top of the table) are Jake Woodford, Giovanny Gallegos, Seth Elledge, Carlos Martínez and Johan Oviedo. Some, like Kwang Hyun Kim and Adam Wainwright (the latter admitting to doctoring baseballs in 2019, but implying he hasn’t since), also have lower spin rates on various pitches, but with more modest decreases. Then there are pitchers with virtually no change, if not slight increases. An example of this is John Gant, whose higher four-seam and curveball spin rates might be explained by his transition from the rotation to the bullpen.

Like I said earlier, I’m not going to try to use this data to confirm or deny anything. Other factors like nagging injuries can also affect spin rate, so apporach these numbers however you please. One thing that is certain is this: spin rates are down across the board, and MLB’s latest enforcement efforts are presumably having a nonzero effect.