To make room for Snyder on the 40-man roster, Boston transferred catcher David Ross to the 60-day disabled list. Ross had been on the seven-day concussion DL for the past week, his second stint on that list this season.
As Middlebrooks continued to slump -- he's hitting just .192 this season with nine home runs and 25 RBIs -- the Sox couldn't justify playing him over the red-hot Iglesias on a regular basis.
"This became about Will getting regular at-bats," Red Sox manager John Farrell said. "He's an important part of us today as much as he is going forward, and for him to get back on track to make an impact with us he needs everyday at-bats."
He added, "The play of Iglesias has as much to do with becoming the third baseman in the short run as anything."
Farrell set no timetable or performance benchmarks for Middlebrooks to return to the Major Leagues, meaning he could be in Triple-A for the foreseeable future or at least until Iglesias, who's batting .426 in 33 games this season entering Tuesday's game, cools off.
"[Middlebrooks'] skills haven't gone backwards," Farrell said. "He's still a very talented player. The consistent work will allow him to reproduce the swing that he showed last year and showed throughout the course of Spring Training and recognizing that this year there will some struggling for him but this is not uncommon for a young player. To take a step back now for the bigger picture, he's finding his way to becoming a Major League player and part of that sometimes requires taking a step back and this is exactly what's taking place."
Middlebrooks was a bright spot for Boston in 2012. In his first taste of the big leagues, the former fifth-round Draft pick hit .288 with 15 homers in 75 contests. But after a slow start to the season, Middlebrooks missed 16 games in late May and early June with a lower back strain, giving Iglesias more opportunities. When he came back, Farrell said the two infielders were in a competition, and for at least the short term, it appears Iglesias has won.
"Competition is going to reveal that maybe one guy is ahead of another and you can't deny the fact that we got a guy that's getting multiple hits a game for a period of time, and for the short run, [Iglesias is] our third baseman," Farrell said.
Snyder, who joined the Red Sox on March 31, will be used as a utility man at first and third base to give regular starters an occasional day off. The 26-year-old batted .267 with 10 homers and 37 RBIs in 63 games for the PawSox. He leads the club in runs and doubles. A first-round selection by Baltimore in the 2005 Draft, Snyder has appeared in 56 Major League tilts with the Orioles and Rangers. He sports a career .276 average with three homers in 98 big league at-bats.
"I'm just here to help keep the wheel rolling," Snyder said. "Obviously they're doing good and I'm just here to help fill the creases."