Francona said Chamberlain had been battling soreness in his left side for a couple of weeks, and after Sunday's outing, the pain became worse. Chamberlain's diagnosis is a intercostal strain, and he is on the 15-day DL, retroactive to Sunday.
"We looked at him again today, and there's improvement, but probably not to the point where he could pitch tonight," Francona said.
In addition to Monday's doubleheader, the Indians face a quick turnaround from a night game Tuesday to a day game Wednesday, so pitching could be at a premium. Francona wanted the maximum number of arms available, plus a reliever capable of throwing multiple innings in case there is a short start.
"We disabled [Chamberlain], and we called up Merritt, just in case we need some length," Francona said. "The one thing we try to be protective of is our bullpen. Once you go too far, you can't take it back."
Chamberlain has a 1.93 ERA in 14 appearances this season. Merritt comes to the Indians after going 3-4 with a 2.94 ERA in eight starts with Triple-A Columbus. He has never made an appearance in the Major Leagues, but Francona said reports on Merritt indicate he has been pitching "very well."
Anderson is 0-3 with a 7.99 ERA in seven games (six starts) for the Indians this season. He took the loss against the White Sox on April 9 in his season debut, allowing two runs in six innings.
Brantley progressing Outfielder Michael Brantley will resume taking swings Tuesday. He is on the DL with a right shoulder injury. Francona said Brantley will swing for the next couple of days and get further evaluation when the Indians return home later this week.
"When we get home, we'll get our eyes and let the medical people see him and start the progression," Francona said. "But it seems like all is well."
Carrasco to begin rehab stint Right-hander Carlos Carrasco, recovering from a left hamstring strain, threw three innings in a simulated game Monday and threw 10 more pitches in the bullpen after. Francona said Carrasco will make a three-inning rehab appearance Saturday with Class A Lake County.
Cody Stavenhagen is a reporter for MLB.com based in Chicago.