Tyler Thornburg suffers another setback

BOSTON — The mystery deepens for Tyler Thornburg.

The man acquired to be Boston's set-up man has still yet to throw a pitch in a game this season, and after another setback this past week, doesn't appear projected to throw off a mound anytime soon.

Thornburg was shut down from long toss after pain in his shoulder persisted. The right-hander still hasn't thrown beyond 120 feet, and he hasn't pitched off a mound since the spring.

"The symptoms have not completely subsided," manager John Farrell said. "We are continuing to gather as much information as possible on what's going. I know that’s been a recurring answer to the question about Tyler."

Asked if surgery were on the table, Farrell said it has not been recommended.

"Until further notice," he said, "this is where we are."

The absence of Thornburg has thrown a major wrench into Boston's preseason plans for the bullpen. Without Thornburg, the Red Sox have relied heavily upon the four remaining right-handers in their pen, with Craig Kimbrel, Matt Barnes, Heath Hembree and Joe Kelly shouldering a large portion of the load.

While the bullpen has pitched exceedingly well this season, all four right-handers mentioned are on pace to pitch more than 70 innings this season. The issue is season-long sustainability, especially with a rotation prone to some brief starts.

Kimbrel hasn't pitched 70-plus innings since 2011; he hasn't hit 60 since 2014. Hembree's crossed the 60-inning threshold once as a professional, when he threw 63 frames in 2013. Barnes and Kelly are converted starters; while the innings workload isn't as arduous on them, the frequency of appearances remains less familiar.

The Red Sox have counted on getting Carson Smith back for the second half of the season, but it's unclear just how much they can lean on someone who hasn't pitched much in the last 20 months.

Smith's scheduled simulated game on Tuesday was postponed a day due to residual soreness in his lat; Farrell downplayed it, saying a rehab assignment this weekend remains a possibility.

Smith's rehab assignment figures to be longer than typical for a reliever, given the length of time missed. Under the new collective bargaining agreement, pitchers coming off Tommy John surgery can rehab for up to 60 days, instead of the usual 30.

For context, San Diego's Carter Capps exhausted all 60 days of his rehab schedule before being optioned to Triple-A to continue to work his way back from his March 8, 2016 surgery. Smith's surgery was May 24 of last year.

While the Red Sox don't expect Smith to take that long, this won't be a two-to-three game rehab the way it often is for relievers.

"This is a little bit different, because he's missed a year and a half," Farrell said over the weekend. "We're still going to have to monitor how he's coming out of increased intensity, maybe the frequency. We've got some things to accomplish with Carson."