Sean Manaea Returns to the Bay, Signs With Giants

It’s been a relatively quiet offseason for the San Francisco Giants, who signed outfielder Mitch Haniger but have come up empty on bigger names including Trea Turner, Kodai Senga, and, most notably, Aaron Judge. On Sunday, though, they got back in action, inking a deal with left-handed pitcher Sean Manaea for two years and $25 million, with an opt-out after 2023.

At age 30, Manaea tested the open market as a free agent for the first time in his career. In 885 career innings, he has almost defined what it means to be a league-average pitcher, with a 4.07 ERA (99 ERA-) and 4.06 FIP (98 FIP-). While he’s made 30 starts in a season just once and missed almost the entire 2019 season with injury, he’s been consistently available throughout his career and has averaged over 5.5 innings per start, well above average in today’s game. While Manaea had a very good 2021 season, during which he set a career high in strikeouts while walking a minuscule 5.4% of batters and posting an 88 FIP-, his performance largely regressed after being traded to the Padres just before Opening Day this year. His strikeout rate fell, his walk rate went from elite to average, and his home run rate spiked, leading to a career-worst 4.96 ERA even in a lowered offensive environment.

So what caused this significant regression in performance? First, let’s examine Manaea’s pitch mix. The bread and butter of his arsenal is a low-90s sinker that he throws over 60% of the time, but its true shape lies somewhere between that of a sinker and a four-seam fastball. In 2022, the pitch had 2.4 fewer inches of drop than other sinkers thrown in the same velocity band, with about an inch less horizontal run.

In addition to having more hybrid movement characteristics, the way Manaea uses his sinker is a bit different from the way most hurlers do. Sinkerballers usually pitch low in the zone, itching for weak groundballs that limit damage and maximize double plays. While the average sinker is thrown 2.37 feet off the ground, Manaea fires up in the zone, with a 2.82 average pitch height. Just two other pitchers in baseball threw sinkers with a higher average height than Manaea in 2022 – George Kirby and Drew Smyly. The league average four-seamer height of 2.81 matches up almost perfectly with Manaea’s game plan. The end result is that Manaea induces far fewer groundballs than the average two-seam artist. Manaea’s arsenal (sinker, slider, changeup) generally results in a very groundball-heavy profile because of the east/west and downward movement of each pitch type. Comparing him to other starting pitchers with the same arsenal shows just how much of an outlier Manaea is:

While some of these names dominate the groundball leaderboards, Manaea ranked in the 25th percentile in this metric, which hurts him because he’s always had a higher-than-average HR/FB rate. His 1.65 HR/9 ranked second-highest among all pitchers with at least 130 innings, and that rate far surpassed anyone else with a similar pitch arsenal. Manaea has allowed 54 homers over the past two seasons, and his sinker has accounted for about two-thirds of them. This isn’t just due to his tendency to throw them high — it’s also due to the pitch’s subpar shape. The movement profile is one of the most important parts of evaluating any given pitch, and for fastballs and sinkers, pitchers either want to have far more rise than run or vice versa. Unfortunately, the hybrid shape of Manaea’s sinker gives it equal amounts of both axes of movement, creating a very predictable shape that allows hitters to barrel it up:

Another element of Manaea’s regression was his disproportionately poor performance against opposite-handed hitters. While Manaea held lefties to a very solid .270 wOBA, right-handed batters slashed .273/.322/.494 against him with 25 home runs, good for a .349 wOBA. To examine why this split was so large, let’s take a look at the rest of his arsenal:

The first thing to note is that Manaea actually threw sinkers at a higher rate against right-handed opponents, unusual for a pitch that has a very large platoon split. In the fastball shape article linked above, Kevin Goldstein wrote, “Because the [sinker] has significantly more horizontal movement than four-seamers do, that different-than-normal shape is essential, otherwise one is intentionally moving the ball into the natural bat path of opposite-handed hitters, creating sizable platoon splits.” Given that Manaea’s sinker is as dead zone as it gets, it’s not hard to see why it has experienced subpar results against righties.

The performance of Manaea’s changeup is also important to understanding his exaggerated platoon split. A good changeup is probably the best tool a pitcher has to neutralize opposite-handed competition, and I’ve previously explored pitchers generating reverse splits by weaponizing their changeups and splitters against opposite-handed hitters. Earlier in his career, Manaea was incredibly effective at maximizing the vertical separation between his sinker and slowball. In each of the seasons from 2016-18, his changeup had more than seven more inches of vertical drop than average. From 2019-21, the cambio lost a bit of its downer action, but still dropped more than average. In 2022, however, it had an inch less vertical movement than average for the first time in his career, and the poor results followed. In 2021, Manaea’s best pitch was the changeup, registering a -1.4 run value per 100 pitches according to Baseball Savant. This year, that number basically flipped. Opponents slugged .528 against the pitch and generated a +1.8 run value per 100 changeups. Without the characteristic drop of a changeup, Manaea’s two main offerings against righties were sinker and “slower sinker,” and hitters predictability capitalized on that.

It’s not all bad news with Manaea, though. While his 4.96 ERA and 4.53 FIP were the worst of his career, his 3.90 SIERA and 3.96 xFIP were right in line with his career numbers. It’s certainly likely that some degree of fly ball regression will occur – while his 13.1% career HR/FB is a bit higher than average, his 14.9% mark in 2022’s deadened environment is likely to drop a bit in the future. Furthermore, Manaea has always leveraged his home ballparks to limit the damage done by aerial contact against him. Statcast park factors rate Oakland and San Diego as the second- and third-most pitcher-friendly ballparks in baseball, and his career ERA is about three-quarters of a run better at home. Oracle Park actually graded out as a neutral park this season, but it still ranked fourth best at suppressing home runs. If we look just at the performance of right-handed hitters, who Manaea has shown a weakness against, San Francisco actually becomes the second-best stadium for pitchers trying to keep the ball in the park. Oracle also ranks favorably when looking at all fly balls from righties, whether or not they leave the park:

Even with his poor 2022 performance, Manaea still maintained a 3.62 ERA at home despite worse strikeout and walk numbers compared to on the road, largely due to fewer batted balls leaving the yard in the confines of Petco Park. However, the largest cause for optimism for Manaea is the Giants’ strong track record of developing and improving pitchers similar to him. Take another look at the table of sinker/slider/changeup pitchers at the top of this article – you’ll notice that four of those six pitchers now play for San Francisco, and each of Webb, Wood, and Junis have made significant improvements during their time in the Giants organization. Webb has leveraged the power of seam-shifted wake to extraordinary success with his sinker and changeup. Between 2020 and ’22, he added an additional seven inches of drop to his sinker despite throwing it at the same velocity, while his changeup experienced a similar gain. The Giants will likely try to develop similar seam-shifted wake characteristics in Manaea to improve the shape of his changeup and transform his two-seamer into a true sinker shape to help him induce more groundballs, similar to the way Webb did.

Another way in which both Webb and Wood have succeeded with their sinker-based arsenals has been through dropping their release point. Last year, Ben Clemens wrote about the effectiveness of sinkers with a lot of drop and a low release point. As Ben pointed out, the Giants dropped Wood’s arm slot to produce a flatter sinker, while they were able to mold Webb’s delivery in the minor leagues. They won’t have to make any big alterations to Manaea’s mechanics, though, as his average vertical release point of 5.3 feet was one of the lowest in baseball this season. The only starting pitchers with release height under five feet? Alex Wood and Logan Webb. Junis hasn’t altered the shape of his pitches, but dropped his FIP by a full run after shelving his four-seamer in favor of more sliders. Manaea is also a candidate to reduce his fastball usage in favor of more secondaries.

When teams seek out free agents, they’re not buying past production – they’re investing in future results. The Giants have shown a clear willingness to tinker with the skill sets of established major league players, and they have a track record of success improving many pitchers with Manaea’s profile. While they may have missed out on Judge and Senga, much of their recent success has been characterized by maximizing the effectiveness of non-star players, and with the right tweaks to his approach, Manaea could very well regain his form as a consistent above-average starter.