One of the Red Sox’s priorities this offseason was to secure a No. 2 starter to pair with ace Garrett Crochet . To that end, the club swung a Nov. 25 trade with the Cardinals for Sonny Gray .

Skeptics may question whether the Gray trade actually achieved Boston’s goal, considering Gray is a 36-year-old whose 4.28 ERA in 2025 ranked 50th among the 70 pitchers who threw at least 150 innings.

However, Gray’s ERA only tells a small part of the story. While his age may make him more prone to regression and injury, the numbers suggest the three-time All-Star still profiles as a high-end starter.

SIERA (or Skill-Interactive ERA) is one of the best advanced metrics we have at our disposal for evaluating a pitcher’s performance and projecting future success. You can read more about SIER

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