Inner Half

Jon Heyman via X dropped the news that St. Louis Cardinals starting pitcher Sonny Gray had been traded to the Boston Red Sox. You felt like this was coming for the Red Sox in that they were going to make a run either at a premier free agent starter or be active on the trade market looking for the same return. It’s happened, and it’s the 36-year-old, 5’10” right hander that will slot in behind ace lefty Garrett Crochet in their rotation. 

Jeff Passan reported St. Louis will send $20 million in cash to the Red Sox to help cover Gray’s 2026 salary. Additionally, Gray’s contract is being restructured a bit. Originally having signed a 3-year, $75M deal with a $35M salary for 2026, Gray will now see his salary for 2026 reduced to $31M with a mutual option buyout in 2027 for $10M. Essentially, Sonny Gray will be paid $41M for 2026. With the Cardinals sending $20M along with him, the Red Sox will be paying about half of Gray’s money, so around $11M for the salary, and $10M buyout. MLBTradeRumors says it’s been more than a decade since a mutual option was exercised by both sides in MLB. Lotta numbers, I know.

Full Trade Details:

Red Sox receive: SP Sonny Gray + $20 million cash

Cardinals receive: LHP Brandon Clarke (BOS #5 prospect, MLB Pipeline) and RHP Richard Fitts 

What did Boston get here?

Boston’s essentially getting Sonny Gray for one year and $21M. The restructuring of the deal tells us this union is a one-year rental, as mutual options rarely get exercised, and Sonny Gray should perform enough to warrant $10M+ next year, assuming the 36-year-old keeps it going.

The Red Sox had the 12th-best ERA (3.92) from starting pitchers in 2025, as well as the 9th-most innings (863.0) out of their starters. The innings piece is key because it lessens the load on volatile bullpens. However, despite having a rotation ERA in the top half of baseball, Boston’s xERA was about .4 runs more at 4.36. xERA takes into consideration exit velocity and launch angle, essentially telling us that the quality of contact from opposing hitters probably should have resulted in Boston allowing more runs. Great defense helps to mitigate that, of course, and Boston’s defense was also top half of the league by Outs Above Average (OAA) and Defensive Runs Saved (DRS). 

With Gray, the Red Sox get another proven veteran star that can get them to that next level of the playoffs. The Red Sox, this past postseason, were forced to put young arms on the mound like Connelly Early, because of their lack of starting pitching prowess at the end of the season. Outside of Crochet, Brayan Bello, Lucas Giolito, the Red Sox didn’t have a set rotation. Gray gives the Sox a reliable arm that’s eclipsed 166 innings or more each of the last 3 seasons. 

Gray’s 2025 numbers suggest he took a dip in performance, but the underlying numbers would tell us otherwise. Per Fangraphs, Gray started 32 games and threw 180.2 innings to a 4.28 ERA (3.90 xERA) and a 3.39 FIP (3.07 xFIP). The staggering difference between actual runs allowed and expected would lead us to say that Gray performed a lot better than his ERA. With the 3rd-highest BABIP in the league, it’s likely Sonny Gray just had flat-out bad luck in 2025 because the Cardinals defense, by OAA, was actually number one in MLB. Among SPs, his 21.6% K-BB% (strikeout rate minus walk rate) was 7th-best in baseball. We’re talking about an elite arm, which given his size, has been sold short across the league. 

While we’re on the topic of his size, being a 5’10” major league pitcher requires strategy. He doesn’t have elite velocity and he won’t intimidate hitters upon first glance. What he does is fool hitters. Utilizing breaking pitches to his advantage is something he has had to lean on. That means his curveball and sweeper. He threw those pitches 18-19% of the time last season, and to great results. The sweeper gave up a .151 BA (.154 xBA), .241 SLG (.250 xSLG), .174 wOBA (.180 xwOBA), and in my opinion the most impressive part was the 42.4% Whiff% (swing and miss). The curveball was slightly worse but still a very good pitch, with both achieving 5+ run values. 

What I mean to say with all these numbers is that Sonny Gray is an underappreciated pitcher. He’s been a member of a mediocre Cardinals team entering a rebuild and will have a chance to shine in Boston as their #2 arm.

What this means for St. Louis

For a Cardinals team that finished 78-84 last season, 19 games back of the first-place Brewers and 14 games back of the wildcard Cubs, something had to change.

As vague as that sounds, what should be clear is that this team was not in a window of contention that fit Sonny Gray’s timeline. Gray stood out like a sore thumb in that rotation, surrounded only by guys like Andre Pallante (-1.2 bWAR), Miles Mikolas (0.4 bWAR), Matthew Liberatore (1.0 bWAR), Erick Fedde (-0.1 bWAR) and Micheal McGreevy (0.7 bWAR). Going forward, St. Louis feels that focusing on younger pitchers like Pallante, Liberatore and McGreevy is best.

In return for Gray, St. Louis adds a couple of young arms, as well. 25-year-old right-hander Richard Fitts, a former 6th round pick (183rd overall) of the Yankees, debuted for the Red Sox in 2024 and made 10 starts in the bigs in 2025. Fitts was the 12th ranked prospect in Boston’s system before debuting in ‘24, according to MLB Pipeline, where they projected him as a potential MLB back-of-the-rotation starter or multi-inning reliever with potentially two plus pitches in his fastball and slider. 

The other arm coming over to St. Louis’s organization is 22-year-old left hander Brandon Clarke, Boston’s 5th round pick (148th overall) in 2024. Clarke’s first full season was split between A-ball and High-A (A+), with the latter seeing the majority of his starts. In 11 starts and 28.1 IP, he threw to a 5.08 ERA, striking out 43 and walking 25. He only allowed 15 hits, none of which were home runs. 

Clarke should be viewed as the more valuable return of the two in this case, as he’s just 22 and he’s got strong physical traits being 6’4”, 220. MLB Pipeline calls his slider “devastating,” which he pairs with a fastball that can touch 100 mph, but also forewarn that he is very much a work in progress with a high ceiling, but also the risk that he tops out as a relief arm in the big leagues. He slots in as the Cardinals #7 prospects.

What this indicates for St. Louis is obviously their desire to get younger. They signed Gray, as well as acquired other veterans like the great Nolan Arenado, in hopes to contend for a World Series, however that hope has quickly faded. In Gray’s first year with the team in 2024, they managed just an 83-79 record and no playoff spot. They haven’t reached the playoffs since 2022. 

Watch out for Nolan Arenado to be traded in the coming months, as well as other key pieces in hopes that the Cardinals get a full return and gun for a full rebuild. A trade could also be in the form of former Gold Glover and 2025 All-Star Brendan Donovan or 3-time All-Star catcher Willson Contreras. 

The Cardinals have the 5th-ranked prospect in baseball in infielder J.J. Wetherholt, who’s expected to debut in 2026, the 36th-ranked prospect in left-hander Liam Doyle, whom they drafted 5th overall in 2025 and is expected to debut in ‘27, the 55th ranked prospect in catcher Rainiel Rodriguez, still just 18-years-old and expected in ‘28, as well as the 92nd prospect Leonardo Bernal, a switch-hitting catcher expected in 2026. 

Clearly, St. Louis will look a lot different at the big league level come 2026, assuming one or more of those veterans are also traded in addition to Gray, as the Cardinals look to retool their way back to contention in the NL Central, a division currently being dominated by the Milwaukee Brewers and Chicago Cubs.