O'Sullivan signed a minor-league contract with the Nationals on Sunday, Connor Byrne of MLBTradeRumors.com reports.

EDGE Analysis

O'Sullivan will return stateside after opening the season with the Nexen Heroes of the Korean Baseball Organization. Nexen granted O'Sullivan his release in May after the right-hander served up 14 runs over eight innings, but it appears the Nationals think he could still fortify the team's pitching depth at Triple-A Syracuse. O'Sullivan last appeared in the big leagues in 2016 with the Red Sox, making five appearances and turning in a 6.75 ERA.

O'Sullivan (knee) was activated off the disabled list Thursday, and outrighted to Triple-A Pawtucket, Evan Drellich of the Boston Herald reports.

EDGE Analysis

O'Sullivan had been on the DL for just over a month after dealing with left knee tendinitis. He recently completed a rehab assignment with Pawtucket, but was roughed up pretty good, allowing six runs on six hits in three innings. The team decided to keep him with the Triple-A team, but O'Sullivan will likely come back to the majors before the end of the month.

O'Sullivan allowed six runs on six hits in three innings during a rehab start at Triple-A Pawtucket. He struck out four and didn't walk a batter.

EDGE Analysis

O'Sullivan lasted just 53 pitches before getting yanked. The right-hander, who had a few starts in Boston when the Red Sox had some problems at the back end of the rotation, is expected to be assigned to Pawtucket when he's ready to come off the disabled list.

O'Sullivan (knee) will make a rehab start with Triple-A Pawtucket on Thursday, Ryan Hannable of WEEI reports.

EDGE Analysis

While his rehab seems to be progressing well, with the trades the Red Sox have made at the deadline, it seems O'Sullivan likely won't get a starting spot once he's back. Depending on how well he pitches from the bullpen, it will determine his value moving forward.

O'Sullivan was placed on the 15-day DL on Saturday with left knee tendinitis, Tim Britton of the Providence Journal reports.

EDGE Analysis

This move conveniently opens up a roster spot for Brad Ziegler, who is expected to be activated Sunday. O'Sullivan has struggled in 21.1 innings with the big club this year, but the Red Sox have won in all four of his starts with the offense exploding for 39 runs in those four games. It's entirely possible O'Sullivan will return to a starting role once healthy, but his window to start may shut in a hurry as the Red Sox figure to be in pursuit of rotation help at the trade deadline.

O'Sullivan didn't factor into the decision versus the Rays on Friday, giving up four earned runs on seven hits and a walk over five innings. He struck out four.

EDGE Analysis

After 93 pitches over five innings and having seen a 4-2 lead evaporate, manager John Farrell didn't want to push his luck with the erratic O'Sullivan. The veteran righty's performance was serviceable, but he did give up a Brad Miller sacrifice fly and Evan Longoria RBI single in his final inning of work, allowing the Rays to erase a two-run deficit. It remains to be seen if O'Sullivan will hang on to his rotation spot following the All-Star break.

O'Sullivan will start Friday's game against the Rays, Brian MacPherson of the Providence Journal reports.

EDGE Analysis

It came down to O'Sullivan or Clay Buchholz, and O'Sullivan earned a second start after he carried a shutout into the sixth inning of Sunday's win over the Angels. An additional factor was that manager John Farrell liked the idea of having Buchholz available out of the bullpen a day earlier than O'Sullivan would be available. We're taking this one day at a time with O'Sullivan as the fourth starter. Presuming he pitches well Friday, he'll remain in the rotation following the All-Star break.

O'Sullivan allowed two runs on four hits and three walks while striking out two in Boston's win over the Angels on Sunday.

EDGE Analysis

The Red Sox were in tatters following Saturday's embarrassing 21-2 loss. Apart from Saturday's ignominy, Boston's starters have pitched poorly of late and the bullpen taxed. So it was the journeyman O'Sullivan, called up from Triple-A to make a spot start, given the responsibility of stabilizing the team, and he did just that. It was an effort that earned him the adulation of Fenway Park and most likely another start this coming Friday against the Rays. Beyond the top three in the rotation -- David Price, Rick Porcello and Steven Wright -- the Red Sox are looking for someone, anyone, to grab hold of the final two spots.

O'Sullivan's contract was purchased from Triple-A Pawtucket, MLB.com reports. He'll get the start Sunday against the Angels.

EDGE Analysis

The Red Sox have been able to get by with a four-man rotation of late due to scheduling quirks, but with the team in the midst of a stretch of six games in as many days, O'Sullivan was needed to make a spot start. The team could surely use O'Sullivan to eat some innings after starter Clay Buchholz and the bullpen were pummeled for 21 runs in Saturday's loss, but don't count on pretty numbers from the right-hander, who has surrendered 10 earned runs on 19 hits and two walks over 11.1 innings with the Red Sox this season.

O'Sullivan is scheduled to start Sunday's game against the Angels, Evan Drellich of the Boston Herald reports.

EDGE Analysis

O'Sullivan, who's Triple-A start on Thursday was skipped in preparation for this move, made 11 starts for Triple-A Pawtucket this season and sparkled, posting a 6-2 record with a 2.79 ERA over 71 innings. He'll now have a chance to carry over his minor league production Sunday as he faces off against Matt Shoemaker and the Angels.