[UPDATED: 6:12 p.m.]
BALTIMORE — The Nationals placed Denard Span on the disabled list and Jordan Zimmermann on the paternity leave list Friday afternoon, part of a flurry of roster moves before the start of their weekend series against the Orioles.
Infielder Wilmer Difo was recalled from Class AA Harrisburg to take Span's roster spot and give the Nationals another position player this weekend. Reliever Aaron Barrett, meanwhile, was activated off the DL after missing 24 games with a right biceps strain, and will take Zimmermann's roster spot for now.
Span's placement on the 15-day DL — the team officially says he has back tightness — had been surmised for several days. The injured center fielder flew to Dallas on Thursday to be examined by a specialist after a month spent dealing with occasional back spasms and made it clear he did not expect to play at all in this weekend's series.
Manager Matt Williams said the MRI found no structural damage and they believe he will be able to return soon after games resume following the All-Star break.
"It's good news. The results of the MRI and the specialist he saw found nothing alarming, which is good," Williams said. "We have to look at his history and look at the two surgeries he had this winter and say that there's some changes in there. So we have to address them. We have him another set of exercises to further his strength. He'll start that process and he'll be back quickly, so that's a good sign."
That roster move is retroactive to July 7, so Span will be eligible to return as soon as July 22. With the All-Star break next week, he could wind up missing as few as nine games, assuming he's not more seriously injured.
Span expressed worry before he left for Dallas that his back injury was something serious, that it could jeopardize his career. Williams said those feelings are understandable and that Span is relieved to know his diagnosis.
"You can understand that. You don't know why something is happening and you're trying to figure it all out. Some days are good, some days are not so good. All the news is great, that will give him a sense of relief. It is certainly a relief for all of us and it will allow him to get aggressive in his rehab to get back in this short time," Williams explained.
Zimmermann, meanwhile, will start on Saturday. Sunday's starter has yet to be determined, though all indications point to Max Scherzer getting the nod.
Barrett returns to the Nationals' bullpen after missing nearly four weeks with a biceps strain. The right-hander was 3-2 with a 5.06 ERA in 30 games before suffering the injury while throwing a pitch in Milwaukee, but did not surrender a run in four rehab appearances with Class A Potomac.
Barrett's injury looked ominous at the time, and he admitted Friday he was initially worried he had suffered serious damage to his arm.
"A couple outings before that, it was really bothering me," he said. "And then when I pitched in that game, the last five or six pitches, I literally couldn't feel my arm. So it definitely scared me, for sure. I didn't know if it was anything more serious than it was. I think if I would've continued to go on, I think I could've really hurt something more extreme. It could be a blessing in disguise. Hopefully I caught it before it got worse."