Donaldson was in the lineup Sunday afternoon, but instead of getting the start at third base, the Blue Jays eased him back at designated hitter. Prior to the addition of Dominguez, Toronto would have been left without a backup infielder off the bench, with the exception of first baseman Justin Smoak.
Dominguez appeared in three games for the Blue Jays earlier this season but did not have a hit in seven at-bats, and he went 0-for-3 in Sunday's 5-4 win over the Red Sox. He is a career .231 hitter with a .645 OPS over parts of five years in the Major Leagues, with most of that time coming in Houston from 2012-14.
Tepera pitched in four games at the big league level this season. He allowed three runs over 3 1/3 innings, but he made just one appearance since he was recalled from the Minors earlier this week.
The Blue Jays originally wanted to carry eight relievers until Troy Tulowitzki eventually returned from the disabled list. He's eligible to come off the DL on June 13, but with Donaldson's status at least somewhat up in the air, Toronto could not afford to wait that long to return to a four-man bench.
"Ballplayers in general throughout any series can just get jammed a number of times," Blue Jays head athletic trainer George Poulis said in reference to Donaldson. "Every now and then, one or two really sting, and they last. So he unfortunately had a couple of those in a row, and it just flared it up."
Gregor Chisholm has covered the Blue Jays for MLB.com since 2011. Follow him on Twitter @gregorMLB and Facebook, and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.