Do Lefty-Heavy Rotations Fare Better? What History Says About the 2026 Red Sox

As a lefty, it’s easy to spot other left-handers in the wild. We wear watches on our right wrist and typically have ink/pencil smudges on the outside of our left hand. In baseball, the tell is a bit more obvious — you just need to look at a player’s throwing arm. Following the acquisition of Ranger Suárez, the Boston Red Sox have a plethora of left-handed starters on their roster:

• Garrett Crochet
• Ranger Suárez
• Payton Tolle
• Connelly Early
• Patrick Sandoval 
• Kyle Harrison

That’s six lefties, before factoring in right-handers Sonny Gray, Brayan Bello, and Kutter Crawford. Crochet, Suárez, Gray, and Bello are guaranteed rotation spots (barring a potential Bello trade). It begs the question: how rare are lefty-heavy rotations?

To avoid repeating myself, a lefty-heavy rotation is defined as one with three or more left-handed starters who have started at least 20 games. Data spans from 2010 to 2025.

Since 2010, only 26 teams have featured lefty-heavy rotations. The White Sox ran one over four consecutive seasons (2013-2016), the longest streak in the dataset. The Red Sox followed with three straight from 2017 to 2019.

*David Price (1.1 fWAR) was part of the 2017 rotation, but injuries limited him to just 11 starts.

Do southpaw-heavy rotations actually perform better?

From our sample, such rotations do have a small edge. They average 2.5 more fWAR and a 55.3% win rate compared to 52.1% for the rest of the league. The average rotation has just 1.1 lefty starters with 20+ starts. Fielding three is almost triple the norm. The primary advantage lies in pitching depth, not pitcher handedness. Having three quality starters is rare. The Dodgers, Red Sox, and White Sox didn't just wake up one day with them. Their rotations were already headlined by Chris Sale and Clayton Kershaw in their primes.

Duke Wheeler, a former reliever who briefly pitched for the Pirates in 2008,  emphasized, "If everybody is effective and everybody is a little different, it can work out. If you have five quality starters, it really doesn't matter if it's right-handed or left-handed." The 2011 Phillies' rotation proves Wheeler's point. Their fabled Four Aces (and Joe Blanton) accumulated the highest fWAR in history (27.0) with just two lefties, Cole Hamels and Cliff Lee, alongside righties Roy Halladay, Roy Oswalt, and Blanton.

Rotations with four lefties are even rarer. There have only been four rotations in MLB history that featured four left-handed pitchers with at least 20 starts.

Lefty-heavy rotation outcomes vary. Teams need a well-rounded roster to make a deep run in the postseason. The White Sox appear in the top 10 three times (2014, 2015, and 2016), but finished towards the bottom of the American League Central each year. The other seven teams played in October, but their performance varied due to roster construction. The 2011 Rangers had power hitters Josh Hamilton, Adrian Beltre, and Ian Kinsler slug the team to the World Series. The Red Sox’s exit in the 2017 American League Division Series highlighted that they needed a power bat. The next season, J.D. Martinez and Steve Pearce provided thump to their lineup, and the team came out on top with a World Series title. Righty Nathan Eovaldi was also a key contributor on the mound. Then, there’s the 2025 Phillies. Their pitching was strong, but their offense ultimately came up short in a gut-wrenching National League Division Series loss. The 2026 Red Sox are hoping to avoid a similar fate.

With Suárez in the fold, FanGraphs projects the Red Sox to have the best starting rotation in baseball. Garrett Crochet and Suárez anchor the top of the rotation. Payton Tolle and Connelly Early will likely start the season in Triple-A Worcester. When an inevitable injury hits, one of them will be called up. If either reaches 20 starts, the Red Sox could field its first lefty-heavy rotation in six years. 

Pitching depth alone doesn’t win titles. At the plate, the Red Sox rank 21st in FanGraphs projected batting WAR (21.8), and they must strengthen their infield before Opening Day. However, it's clear that this team has built up an inherent advantage by accruing so many arms from the left side — now they need to capitalize upon it.