Using Spin to Identify Two Underrated Free Agents

The pitcher with the highest fastball spin rate in baseball in 2016 was also the first free agent signed this offseason. Maybe that’s just coincidence — Andrew Bailey was re-signed by the Angels to a modest one-year, $1 million deal with incentives, so it’s not like it required a ton of courting — but there are plenty of front offices who’ve designated at least one analyst to comb through the free-agent wires to find a pitcher with good spin rates. Let’s play along.

Of course, we can only play along so much: the major-league front offices have minor-league spin rates easily accessible in their databases, so they don’t have to go looking far and wide for data. Also, spin rates alone don’t tell the whole story, especially when it comes to changeups and sliders. However, we know this: given equal velocities, the fastball with the higher spin rate is superior fastball — and that looks to be true for curveballs, too. (Check the curveball tab of that linked spreadsheet, courtesy Jeff Zimmerman).

Fastballs are easy, so let’s take a look at the best free-agent fastballs by spin. I’m going to add a column devoted to putting that spin in context. Spin goes up with effective velocity, generally.

Spin by Effective Velocity
Effective Velo Ave Spin Rate
<87 2184
88 2186
89 2200
90 2197
91 2222
92 2246
93 2257
94 2246
95 2275
96 2283
>97 2310
SOURCE: Statcast
Effective velocity = what fastball velocity looks like to the hitter, based on where the pitcher releases the ball.

So I bucketed all fastballs by their effective velocity, found the average spin rate, and then compared each player’s spin rate to their effective velocity average, where 100 is average. I’ve sorted the list for Effective Velocity Indexed Spin (EVIS) here.

Free Agents by Effective Velocity Indexed Spin
Pitcher Velocity Effective Velo Spin Rate EVIS FB swSTR%
Jake Peavy 89.5 88.4 2446 112 8.5%
Rich Hill 90.7 90.4 2458 112 12.4%
Casey Fien 93.9 93.4 2501 111 11.1%
Aroldis Chapman 100.7 101.4 2546 110 18.8%
Koji Uehara 87.3 85.7 2407 110 7.9%
Tommy Hunter 95.8 95.9 2457 108 8.5%
David Hernandez 94.4 93.8 2402 107 8.1%
Neftali Feliz 96.5 96.0 2438 107 13.3%
Kevin Jepsen 94.2 93.8 2396 107 7.1%
Blaine Boyer 92.6 91.5 2367 107 8.8%
Bud Norris 94.0 93.9 2391 106 5.5%
Daniel Hudson 96.7 96.4 2415 106 9.7%
Mark Melancon 92.1 92.4 2373 106 5.9%
Jered Weaver 84.3 84.2 2306 106 4.8%
Fernando Rodriguez 93.4 92.8 2381 105 10.9%
SOURCE: Statcast
EVIS = Effective Velocity Indexed Spin, or fastball spin compared to pitchers with similar effective velocity where 100 = average spin at that effective velocity.

That’s a decent spin rate on the four-seam from Peavy, especially when you consider how slow he’s humping it up there these days. He’s actually in baseball’s top 10 by this measure, sandwiched between spin kings Drew Pomeranz and Rich Hill. Last year wasn’t a great year for Peavy, and it came in a pitcher’s park, so the league may not be chomping at the bit for his services. What about making him a reliever? Maybe he could be a sneaky play with more of those four-seamers at his disposal?

We know Rich Hill and Aroldis Chapman will get money, but Casey Fien could also get a major-league deal. Not only did he show elite spin for his velocity, but he also had the second-best whiff rate of his career. Sometimes you have to look past the home runs, especially in a 40-inning sample, even when you’re talking about a pitcher who cleared waivers and was outrighted to Triple-A this past September.

In a way, this methodology could help future teams identify relievers who still have life on their pitches despite iffy results. Anything can happen in a reliever’s sample, but spin rate is more stable in smaller samples and has some capacity to speak on the health of the pitcher. David Hernandez and Neftali Feliz both gave up a few too many homers, and both have struggled with health in the past, but their underlying spin speaks well of their ability to contribute to a major-league pen in 2017.

Jered Weaver’s spin looks average until you look at it in the context of all fastballs under 87 mph. By grouping all of those together, we get 31 pitchers. But it’s still hard to use this finding to advocate the signing of the one guy who averaged 84 mph on the fastball. The only guys with slower fastballs threw knuckleballs, after all.


Best Free Agents by Curve Spin Rate
Pitcher Ave Velo Spin Rate GB% swSTR%
Charlie Morton 80.8 2990 90% 11.60%
Rich Hill 75.0 2831 42% 9.70%
Mark Melancon 81.7 2743 63% 16.50%
Junichi Tazawa 76.2 2661 20% 5.40%
Casey Fien 79.6 2620 0% 3.20%
Jorge de la Rosa 74.0 2616 27% 9.20%
Scott Feldman 76.5 2582 38% 11.10%
Jake Peavy 79.3 2582 39% 19.80%
Tommy Milone 74.6 2545 12% 11.10%
Jhoulys Chacin 78.5 2518 31% 9.00%
SOURCE: Statcast
Average spin rate on the curve was 2308 this year.

The first guy on the list just signed with the Astros today. You’ve heard about the second guy’s curve spin rate ad nauseum by now. The second guy will get good money. The fifth guy has signed with the Angels already. The third guy — Junichi Tazawa — did decently and should get some money and guaranteed years from a team this offseason. Jhoulys Chacin is interesting because he felt to had to shelve that curve in Coors, and it might be his best pitch.

But there in the middle of the list, we have Fien again, who in any other year would probably be headed for a minor-league invite after the year he had. But in the Era of Spin, he might be find himself with a major-league offer in the coming months. And Peavy again! Maybe he should focus on being a four-seam/curve guy instead of throwing eight different pitches.

Fien and Peavy. Peavy and Fien. Both pitchers recorded a curveball spin rate within the top 20% of all pitchers — in addition a fastball spin rate within the top 5%. That’s a great combo on which to rely. The agents of those two pitchers, at least, should bookmark this page for future reference. It may make a difference with the right front office.

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With a phone full of pictures of pitchers' fingers, strange beers, and his two toddler sons, Eno Sarris can be found at the ballpark or a brewery most days. Read him here, writing about the A's or Giants at The Athletic, or about beer at October. Follow him on Twitter @enosarris if you can handle the sandwiches and inanity.

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Is there a publicly available data base for spin? Have not seen a link to these numbers in any of the articles.