So says Michael Baumann of the Ringer.com:
This is a two-horse race between the Nationals’ Juan Soto and Phillies reliever Seranthony Dominguez.
Soto isn’t in the headlines every night anymore, but he’s still hitting .301/.411/.517. And the reason he isn’t up near the top of the rookie WAR leaderboards is because he’s only played in 51 games and because he’s getting killed by the advanced defensive metrics, which are notoriously unreliable, particularly in small samples and particularly for corner outfielders.
Right now, Baseball-Reference has Soto at seven runs below average in 51 games, which prorates to about minus-20 through a full season. Soto is not Mookie Betts, but Carlos Lee on crutches wouldn’t put up a minus-20 in left field. I expect that Soto will win this award, and everyone will walk away happy.
Even so, I’d vote for Dominguez instead. Every so often we have a conversation about what it’d take for a reliever to win the Cy Young, since relievers pitch so few innings they’ll never lead the league in WAR. Dominguez, a reliever who’s thrown just 33 2/3 innings, is leading all rookie pitchers, AL and NL, in fWAR, and he trails only Oakland’s Lou Trivino in bWAR. Dominguez has a 1.60 ERA and nine saves against six walks, and he’s pitching in incredibly high-leverage innings. Dominguez is third among rookie pitchers in WPA, trailing Arizona’s Yoshihisa Hirano and Trivino, both of whom pitch in much lower-leverage roles and have thrown more innings. Dominguez’s gmLI (the average leverage index when he enters the game) is not only highest among rookies, it’s fourth-highest among all relievers.
Dominguez, a multi-inning stopper, is Philly’s bullpen. Closer Héctor Neris got himself demoted after his ERA neared 7.00, lefty killer Adam Morgan and veteran setup man Tommy Hunter have both blown up in big moments, and free-agent signing Pat Neshek missed the first three months of the season due to injury. The Phillies, having just missed out on Manny Machado, are rumored to be interested in veteran relievers like Zach Britton because Dominguez has been forced to hold the roof up pretty much all on his own: