Replacing Marcum on Toronto's active roster is outfielder Adam Lind, who was recalled from Triple-A Syracuse. With Marcum out of the picture for the time being, the Jays will need to promote a pitcher to start against the Braves on June 27 in Toronto.
"This is a blow to the rotation -- that's for sure," Toronto pitching coach Brad Arnsberg said. "He's throwing the ball as well as anybody on the entire staff. But, bumps in the road come, and hopefully we just get good news."
Arnsberg said Marcum has been dealing with discomfort in his throwing arm for the past couple of weeks, but the pitcher didn't believe the issue was too serious. When the problem persisted, the Jays decided it was time to temporarily shut Marcum down in order to get to the root of the injury.
Following Marcum's start on Wednesday, Toronto sent the 26-year-old right-hander to Florida, where he was examined by team physician Dr. Steve Mirabello. The Blue Jays wanted to have Andrews evaluate Marcum to determine the extent of the injury.
"I know that they did an MRI, and Dr. Mirabello wasn't really, really concerned," Arnsberg said. "[Marcum] has been probably nursing it for a couple weeks now, where we knew there was a little something in there. But it never altered him from pitching or anything.
"He kept taking the ball and wanted the ball, and we kept guarding it. We knew that if we gave him the option, if we needed to shut him down, we would definitely do that, but he didn't feel like it was any concern. So, we just kept going."
In 15 starts this season, Marcum had a 5-4 record, but his 2.65 ERA was the second-best mark in the American League and the fourth-lowest among starters in the Majors. Marcum also led the AL with opponents batting .198 against him and a 1.00 WHIP (walks plus hits per innings pitched).
Marcum's 86 strikeouts currently rank second among the Jays' starters, and are the eighth-highest total in the league. Over his past eight outings, Marcum posted a 2.70 ERA, but low run support led to a 1-2 record and five no-decisions. His 98 2/3 innings ranked eighth in the AL on Saturday.
"It's a shame that we're going to lose one of our starters for a while," Jays manager Cito Gaston said. "We're hoping it's not [serious]. We're hoping that he's going have maybe just a little stint on the DL and he'll be back. We'll wait and see on that."
The top candidates to replace Marcum from Triple-A Syracuse include left-handers John Parrish and David Purcey, along with righty Kane Davis. Parrish is 10-0 with a 2.83 ERA, Purcey is 6-5 with a 2.42 ERA and Davis is 6-6 with a 3.30 ERA at Syracuse.