The Pirates have had a rough go of it. After notching three straight Wild Card berths from 2013 to ’15, they saw their production tail off and haven’t made the postseason since. In that time, they also had the second-best pitching staff by ERA and the fourth-best by FIP thanks to a league-leading 51.3% groundball rate. Their rate of burning worms was 2.8 points higher than the second-place Dodgers, the same distance between Los Angeles and the 10th-place Mets.

The Pirates accomplished this by throwing sinkers at a 23.2% clip, separating them from the second-ranked Guardians by 5.5 points, about the same distance between Cleveland and the 10th-place Angels. Coupled with pitch-framing improvements and a move toward more strategic infield positioning, the Pirates experienced a pitching leap that theScore.com’s Travis Sawchik chronicled in Big Data Baseball. This did wonders for a number of hurlers, namely Francisco Liriano, A.J. Burnett, and Edinson Volquez. But others, such as Charlie Morton and Gerrit Cole, only blossomed upon leaving the Steel City.

Pittsburgh’s pitching apparatus isn’t viewed as revolutionary any longer, but they’ve had a solid record with crafty lefties in recent years — think Rich Hill, Tyler Anderson, and Jose Quintana. Marco Gonzales, acquired from the Mariners (via the Braves) along with cash in exchange for a player to be named later, will hope to join that group. Perhaps the soft-tossing southpaw — who, like the Pirates of the 2010s, relies primarily on inducing weak contact — will be the one to reignite something in the Steel City forges.

Okay, probably not, but when healthy, Gonzales can at least amass innings thanks to low strikeout and walk rates. If the Pirates choose to lean into that strength, they could have him reintegrate a sinker that, by some accounts, he abandoned in 2021, due to the pitch’s general tendency to coax fewer whiffs and more slow rollers than the four-seamer.

At the same time, Gonzales’ fastball seems to have become increasingly sinker-like over the past two seasons. Baseball Savant, which has always lumped his sinker in with his four-seamer, tells this story when limiting things to just what they label as four-seamers:

As Gonzales has dropped his release, increasing run and depth (though with slightly less depth in 2023), his heater has performed worse and worse. As I surmised with Kevin Gausman, this change in release may have been implemented with longevity in mind; Gonzales’ extension has increased slightly thanks to the lower release, which could help his velocity play up as he ages. But if there’s one thing that the Pirates have learned after having everyone and their mother throw a sinker in the 2010s, it’s that a one-size-fits-all approach won’t cut it in this age of advanced player development. Gonzales could benefit from more “perceived” velocity, sure, but not if it comes with more of a sinker-shaped fastball.

So the Pirates could have Gonzales throw more sinkers, but the results likely wouldn’t be good. He could still eat innings that way, but a better way to notch more early-count contact — and soft contact at that — would be to lean more on his looping curveball. The deuce, a low-whiff and weak-contact-generating pitch itself, is his only offering that has returned a positive run value, per Baseball Savant, in both of the past two seasons. Understanding this, the Mariners had him throw his curve at a 24.2% clip in 2023, a career high.

The truth, though, is that the curve was a different pitch entirely this past season. It grew much tighter as Gonzales added nearly three ticks, stripping it of a few inches of both vertical and horizontal break in the process. Here’s what it looked like pre-2023:

And what it looks like now:

Those two pitches start on about the same plane, but what was spiked last year now ends up just below the zone. Our on-site pitching models regard the revamped shape fondly, and the tighter break has seemingly unlocked a new tier of control for Gonzales, which could help it become his primary offering:

And this all came as Gonzales’ forearm began to wear out. As MLB.com’s Daniel Kramer reported, the lefty had more and more trouble getting loose in advance of and recovering after each of his starts in 2023. Ultimately, a compressed nerve was the culprit — one that controls pronation, at that. It’s tough to say whether the change in curveball shape had anything to do with it, but it’s worth noting that the turning-over motion associated with wrist pronation is more typical of sinkers (another reason Gonzales should stay away from one) and changeups (the lefty has turned to his change at an above-average clip across his career).

Regardless, the news was about as good as could be given the dreaded and ambiguous “forearm discomfort” Gonzales was initially sidelined with. He did succumb to season-ending surgery, but other pitchers such as Scott Alexander and Brandon Morrow underwent similar procedures and were able to return without major hiccups; their all-important ligaments and tendons remained untouched, as is the case with Gonzales. He seems poised to enter Spring Training healthy and provide some stability for a young staff.

Make no mistake: the Pirates will not playoff bound for the first time since 2015, and Gonzales does little to move the needle, even if he is a bit of a throwback. But the going rate for innings-eaters these days is about one-year and $13 million; Gonzales is set to make $12.5 million in 2024, but with the Braves forking over some cash in the deal, the Pirates’ effective cap hit will be much less. If the southpaw can stay healthy and ride his revamped curve to success, he could provide surplus value in the form of volume for a rotation without any shoe-ins besides Mitch Keller (especially after Johan Oviedo’s injury), or he could provide the impetus for a deadline deal to replenish a system that still ranks just ninth even after drafting Paul Skenes.

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