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 SIERA here, but it basically emphasizes strikeouts and walks while also taking into account the types of batted balls a pitcher allows, and few pitchers last year were as good as Gray at collecting strikeouts and limiting walks.
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Gray had a 21.6-point difference between his strikeout rate (26.7%) and his walk rate (5.0%) in 2025, an elite mark that was the seventh highest among qualifiers. Relatedly, Gray’s SIERA was a full run lower than his ERA at 3.29, which ranked sixth in MLB.
That ranking is impressive on its own, but more telling is the company he was in. In fact, only one other pitcher besides Gray who ranked among the top 11 in SIERA didn’t earn Cy Young votes in 2025.
Lowest SIERA, 2025
Minimum 150 innings
1. Tarik Skubal: 2.71 (won AL Cy Young)
2. Garrett Crochet: 2.86 (2nd in AL)
3. Cristopher Sánchez: 3.02 (2nd in NL)
4. Paul Skenes: 3.10 (won NL Cy Young)
5. Logan Webb: 3.14 (4th in NL)
6. Sonny Gray: 3.29
7. Bryan Woo: 3.30 (5th in AL)
8-T. Yoshinobu Yamamoto: 3.32 (3rd in NL)
8-T. Jacob deGrom: 3.32 (8th in AL)
8-T. Joe Ryan: 3.32
11. Hunter Brown: 3.39 (3rd in AL)
The forecast for 2026 is also encouraging. Steamer, one of the most trusted projection systems around, has Gray at 3.9 WAR, ninth best among pitchers. Crochet checks in third at 5.6, making the Red Sox the only team with two hurlers in the top 15.
Gray is ranked directly ahead of Dylan Cease, who was one of the top free-agent starters on the market this year before signing a seven-year, $210 million deal with the Blue Jays.
Cease’s lofty price tag underscores another benefit of Boston's trade for Gray. Although the Red Sox had to give up two pitchers in the deal, including promising prospect Brandon Clarke, St. Louis sent Boston $20 million to cover part of Gray’s salary for 2026 and the buyout of his $30 million club option for '27. That leaves Boston with just $21 million in guaranteed money committed to Gray, preserving flexibility to address the club’s other major need: adding a middle-of-the-order bat.