The Red Sox placed Wacha on the 15-day injured list Sunday with left intercostal irritation, Chris Cotillo of The Springfield Republican reports.
Though Wacha was scratched ahead of his scheduled start Sunday against the White Sox after experiencing side soreness, the Red Sox indicated that an MRI didn't reveal any major injury. Wacha was thus expected to be ready to go for his next turn through the rotation, but given the right-hander's prior history of oblique problems, the club will opt to err on the side of caution by moving him to the IL. With Wacha now unavailable until at least late May, Tanner Houck is expected to serve as his primary replacement in the rotation.