CLEVELAND - The Cleveland Indians couldn't wait any longer for Justin Masterson to fix his pitching problems.

The Indians placed Masterson on the 15-day disabled list with inflammation in his right knee Tuesday. Masterson, the team's opening day starter, is 4-6 with a 5.51 ERA.

Manager Terry Francona talked with Masterson on Monday after the right-hander allowed five runs and six hits in two-plus innings against the New York Yankees.

"Masty's first inclination was wanting to pitch through it, which we respect," Francona said. "The way it was going, though, we thought we'd DL him and get him some treatment."

Masterson made the All-Star team last season when he went 14-10 with three shutouts. The Indians considered him to be their staff ace going into the season, but Masterson hasn't won since June 8 and has pitched more than four innings once in his last five starts.

Masterson has been dealing with a sore knee most of the season. He was pushed back a couple of days earlier this month, but his results haven't improved.

"It's hard to imagine it would help," Francona said of the injury. "I'm not in his body. When a guy's out there competing, I don't think they think about it a lot, but I don't think it helps."

Masterson was pulled without retiring a batter in the third against New York. He walked three, hit a batter and rarely topped 90 mph in his 54 pitches, throwing only 24 strikes. He has given up 19 runs, 27 hits and 17 walks in 18 innings over his last five starts.

Masterson's short outings have also also put a lot of stress on the bullpen. Francona used five relievers Monday and six a week ago when Masterson didn't record an out in the fourth inning against the Los Angeles Dodgers.

"Maybe two weeks would be best for him and us because he was exiting early," Francona said. "It's hard to keep doing that and keep the bullpen not only healthy, but productive."

Masterson is a free agent after this season. The two sides talked about a contract extension in spring training, but didn't reach an agreement.

Corey Kluber is the only starter who's still in the rotation that opened the season. Zach McAllister and Danny Salazar are pitching at Triple-A Columbus while Carlos Carrasco was moved to the bullpen after four starts.

The rotation includes Trevor Bauer, Josh Tomlin and T.J. House, who all began the season in the minors. The Indians are in third place in the AL Central with a 43-45 record and trail first-place Detroit by 6 1-2 games.

"You're going to need more than five starters," Francona said. "It's a difficult thing to build in depth. You walk a fine line there. I don't think our record is what we want it to be. You can whine about it or you can choose to try to figure out a way to win.

McAllister or Salazar will be recalled to start Saturday against the Chicago White Sox.

The Indians also recalled left-hander Nick Hagadone and catcher Roberto Perez from Columbus and optioned outfielder Tyler Holt to Triple-A. Right-hander Mark Lowe was designated for assignment.