CLEVELAND -- Guardians starter Alex Cobb was placed on the 15-day injured list Thursday with a blister on his middle finger, which could impact Cleveland's postseason pitching plans.

Cobb, who has helped stabilize the team's rotation since being acquired in a July trade from San Francisco, recently developed the blister. He was also sidelined with a broken nail on his index finger.

The team made the move before opening a four-game series against Tampa Bay.

Cobb, 36, is 2-1 with a 2.76 ERA in three starts for the Guardians, who have a 4-game lead over Kansas City in the AL Central. Cobb recently carried a perfect game into the sixth inning against Pittsburgh.

Guardians manager Stephen Vogt has had to juggle his rotation all season because of injuries. The team acquired Cobb and signed Matthew Boyd to add depth and experience to its young staff.

Cobb's debut with Cleveland had been delayed by blister issues he developed while getting ready to pitch after a long layoff following hip surgery in October.

To fill Cobb's roster spot, the Guardians brought up right-hander Andrew Walters from Triple-A Columbus.