Why Aren’t the Giants Throwing Curveballs?

Are the Giants on to something? The results say...maybe.

The Giants’ somewhat surprising, league-leading 78 wins through Tuesday is explainable in large part due to career years from (checks notes)…all of their hitters. Brandons Belt and Crawford, Buster Posey, and Evan Longoria are all poised to turn in their best hitting seasons by wRC+ since at least 2013. With all due respect to the Giants offense and possibly their innovative strategy of (checks notes again)…practicing hitting sliders instead of just fastballs, the pitching has been equally impressive and seemingly out of nowhere, good for 7th in all of MLB by fWAR up to this point in the year.

There’s one unique way in which the Giants’ pitchers have done it so far, though. They’ve almost completely stopped throwing curveballs. 

In fact, the Giants’ rate of pitches that are curveballs, should it hold for the final six weeks or so of the season, would be the lowest rate for a team in over a decade. While MLB pitchers as a whole have been holding steady or increasing their curveball usage since 2015, the Giants have been bucking the trend for the past three seasons, decreasing their usage precipitously year over year.

Curveball %

Season MLB average Giants
2019 10.6 11.2
2020 10.6 6.5
2021 9.9 3.6

 

So, have the Giants figured something out and hacked their way to pitching success? 

Among the starters with more than 20 innings pitched, Kevin Gausman, Logan Webb, and Johnny Cueto are returners from the 2020 squad. Gausman and Webb have never really thrown curveballs, so they’re not much help in determining what’s going on. Cueto, on the other hand, has been with the Giants a long time and has cut his curveballs down, quite significantly over the past few years:

After steadily increasing and reaching a peak in last year’s shortened season, Cueto has almost completely backed off of his curveball this season. 

One of the newer arrivals to the Bay, Alex Wood has not thrown a curveball in two years, though that adjustment was made before he arrived in San Francisco. Until 2019, curveballs had averaged almost a quarter of Wood’s offerings. Then in 2020, Wood abandoned it with the Dodgers completely and hasn’t turned back since. 

The exception in the Giants’ starting rotation has been Anthony DeSclafani, who also is on a three-year downward trajectory with his curveball usage– but again, as a newcomer to the Giants this season that doesn’t tell us much about the Giants’ philosophy. Curiously, his curveball usage has dropped mainly at the expense of more changeups– which have a higher xSLG, xWOBA, and generate fewer whiffs than his curve this season. Historically Tony Disco’s change has been the better offering, however, which might explain the approach this year. 

The bullpen is another story of extremes altogether. Among Giant (the team, not the myth), relievers who have thrown at least 20 innings, not a single one has thrown even one curveball this year! San Francisco is the only team in the majors this year without a reliever to throw a curve (minimum 20 IP).

It’s difficult to attribute this to a specific development philosophy within the Giant organization up to this point. Among the six most-used relievers on the team this season, only Tyler Rogers was with the organization prior to 2020. José Álvarez used to throw a curve, but abandoned it in 2019 when he was with the Phillies.

What should we make of all this? First, it’s clear that the Giants are not acquiring players and scrapping their curves altogether, as Desclafani demonstrates. It’s possible that coincidentally the Giants have a collection of players that don’t throw a bunch of curves, but the year-over-year downward trajectory as MLB’s curve rate basically holds steady suggests otherwise. One explanation is that the Giants are awfully lefty-heavy in their bullpen, at least. Lefties get less spin and movement on their pitches, on average, so perhaps there’s a bit of selection bias in the Giants’ sample. 

Whether the Giants have a hypothesis regarding pitcher health (only six teams have used fewer starters than San Francisco this year) or believe there’s a competitive disadvantage in curves, they do seem to be avoiding them.

The Giants may be moving away from acquiring players who throw curves, as that’s likely easier than asking a player to scrap a pitch with which he’s had some amount of success in the past. It will be fascinating to watch Giant farmhands come up in the next few seasons to see what their arsenals look like; if the team continues to demonstrate this kind of success in the NL West while throwing historically low rates of curves, it may be that the Giants are on to something after all. 

 

Photo by Dustin Bradford/Icon Sportswire | Adapted by Aaron Polcare (@bearydoesgfx on Twitter)

Sean Roberts

Sean Roberts is a contributor to Pitcher List and writes mostly about the Brewers at Sausage Racing Form. His work has been featured on Baseball Prospectus, the Hardball Times, and October. He's still getting used to the DH in the national league.

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