To make room on the roster, righty Anthony Varvaro was designated for assignment and outfielder Jackie Bradley Jr. was optioned to Pawtucket.
This was the fifth straight day the Red Sox have made at least one roster move, most of them stemming from the struggles of the starting rotation, which has in turn spent the bullpen.
"Obviously we needed the ability to have not only fresh arms, but another pitcher who is capable of multiple innings, and that's where Hinojosa comes into the mix," said Red Sox manager John Farrell.
Why did the Red Sox let Varvaro go?
"It was a matter of fit and the ability to attack right-handed hitters," said Farrell.
Righties were hitting .346 against Varvaro, while lefties hit him at a .263 clip. Varvaro had a 4.09 ERA in nine appearances.
The lack of innings and performance from the rotation has caused an obvious ripple effect in the bullpen.
"You come out of Spring Training with the intent that you're going to define roles as best possible," said Farrell. "So there's a trickle-down effect from inconsistent outings as far as length from a starter. Many times, you're going to the reliever who is rested rather than the matchup. Unfortunately, that's been the case through different turns through the rotation."
Ian Browne is a reporter for MLB.com. Read his blog, Brownie Points, and follow him on Twitter @IanMBrowne. This story was not subject to the approval of Major League Baseball or its clubs.