Shortstop Stephen Drew could be stuck at four games played this season for some time. The recently re-signed veteran aggravated his right oblique injury in Baltimore on Wednesday and after a workout yesterday, may need to visit a hospital today for an MRI. The club is determined to get ahead of the injury, if only to get an idea of what kind of return on its $10 million investment it will get from Drew. “Yesterday in the second round of (batting practice), he felt the right oblique kind of grab him again,” said manager John Farrell. “Whether or not the MRI is needed tomorrow, and even if there’s any question, we’ll get it to get all the information possible. He’s frustrated by it. At the same time, we can’t risk any longer-term situation here.” The Red Sox have not switched Xander Bogaerts back to shortstop in Drew’s absence, opting to keep the rookie at third base. However, Bogaerts had last night off following a tough road trip — 7-for-38, .184 — when Farrell reported detecting signs that the club’s stretch of 38 games in 39 days was catching up to the 21-year-old prospect. “Feel like over the last four or five games, you can see maybe a little fatigue and some at-bats that have been uncharacteristic for him — some early-pitch outs, which like I said is not the norm — I just feel he can benefit from a day down,” said Farrell. The manager said he had not seen anything alarming in Bogaerts, but the young player might have fallen victim to the team-wide offensive malaise. “(It was) evident the other night where he grounds into an inning-ending double play with the bases loaded, there might have been a little frustration at that moment because of what we’re living with as a team,” said Farrell. “To say there are certain situations where you can visibly see it or he comes out of his swing or out of his mechanics some way, no, that’s not there. “We’re rotating guys through as best we can to give a breather when needed. Xander got his breather today.”