Alvarez is the fourth Blue Jays starting pitcher to leave with an injury during the past two weeks. The series of injuries have had a devastating impact on the club's rotation, but the Blue Jays are optimistic this one won't be quite as severe.
Manager John Farrell said the move was made for precautionary reasons and remains optimistic that Alvarez won't have to miss a start.
"We don't anticipate that, but we'll make and take every precautionary measure we can to ensure all of that," Farrell said. "His health is first and foremost in our minds.
"But the way he checked out here -- the strength, the range of motion, not really feeling any additional stiffness as the game went on and even into the rain delay. We don't know it fully, we'll have more information tomorrow, but initially, we're optimistic."
Prior to the start of the sixth inning, Alvarez had a lengthy conversation with catcher J.P. Arencibia after just one warmup pitch was thrown. Alvarez then called for trainer George Poulis and Farrell three pitches into the frame.
Alvarez had difficulty getting loose and when the discomfort began to surface, he opted not to take any chances, considering the current state of the Blue Jays' starting staff.
"I felt a little bit of pain in my elbow," Alvarez said through interpreter Luis Rivera. "Knowing the situation that happened before, I was trying to be a little cautious with that instead of continuing to pitch.
"I'm not too worried about that. I'm going to go to Florida tomorrow, I'm going to get an MRI, hopefully it's not serious, but I'm going to come back tomorrow after the MRI and hopefully I won't miss any starts."
Toronto has already lost right-handers Brandon Morrow, Kyle Drabek and Drew Hutchison to the 15-day disabled list. Drabek is out for the year because of Tommy John surgery, while Morrow and Hutchison are both expected to miss an extended period of time.
The Blue Jays' lone starter who has yet to go down with an injury this season is ace left-hander Ricky Romero. Toronto has already inserted Brett Cecil, Jesse Chavez and Aaron Laffey into the rotation, and the club is running out of options at the big league level.
Those recent events caused a lot of personnel in the clubhouse to initially fear the worst-case scenario, but after Alvarez was evaluated by the training staff, that no longer appears to be the case. A final diagnosis won't be known until late Tuesday, but it's possible the club has avoided yet another serious setback.
"I wouldn't categorize it as an injury right now, even though he left the game with some stiffness," Farrell said. "It's on the inside part of the forearm. I wouldn't say it's over the ligament area, but the MRI will indicate more tomorrow."
Alvarez entered Monday's game with a 3-6 record and 4.30 ERA in 14 starts. He has struck out 27 and walked 20 during his 90 innings of work this season.
Following the Blue Jays' victory over the Red Sox, the club announced it had selected the contract of Scott Richmond from Triple-A Las Vegas. The veteran right-hander was added to the club to provide the Blue Jays with another reliever that has the ability to go multiple innings.
Right-hander Robert Coello was optioned to Triple-A, while Hutchison was placed on the 60-day disabled list to make room for Richmond on the 40-man roster.
The Blue Jays also signed veteran left-hander Jamie Moyer to a Minor League contract on Monday. Moyer will report to Triple-A Las Vegas, where he is expected to join the starting rotation. He is not on a guaranteed deal and has not received any firm commitments from the club about a potential role in Toronto, but he does provide organizational depth.