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7/25/2013 7:32 P.M. ET

Morrow shut down for season with nerve issue

TORONTO -- Brandon Morrow's season has come to an end after he was diagnosed with an entrapped radial nerve in his right forearm during a visit to renowned surgeon Dr. James Andrews.

Toronto's No. 2 starter has been out since May 28 because of lingering soreness in his forearm. He underwent multiple MRIs, but doctors weren't able to find anything structurally wrong.

The loss of Morrow for the rest of the season is another blow to a Blue Jays team that is in desperate need of reliable starting pitching, but at least they now know what's wrong with their hard-throwing righty.

"I think there was speculation, because they couldn't see anything on an MRI, that they thought it was a nerve issue," manager John Gibbons said.

"They look at the MRI, they don't see any structural damage, so the doctors figure it might be something with the nerve. They're always trying to come up with an answer."

Morrow will rest for six weeks before eventually beginning a throwing program. The goal is to have him pitch off the mound by the end of the season, so the club can have a better idea of his progress before closing up shop for the year.

The recovery is key, because the Blue Jays will be relying on him for a return to form next year. He is signed through 2014 with a club option for the following season. Morrow has arguably the best stuff of anyone in Toronto's starting rotation, but he has yet to throw more than 180 innings in any of his seven seasons in the Major Leagues.

Morrow's 2012 season was derailed for more than two months because of a torn oblique muscle, and earlier this year, he battled upper back and neck problems. The forearm issue then surfaced, and despite multiple attempts at rehabbing the injury, he will now require a prolonged period of rest.

"You figure at the end of six weeks, he'll be feeling better, but I'm no doctor," Gibbons said of Morrow, who finishes the season with a 2-3 record and 5.63 ERA in 10 starts.

After moving between positions, Lawrie to stay at third

TORONTO -- The bizarre experiment of moving Brett Lawrie back and forth between second and third base has finally come to an end.

Blue Jays manager John Gibbons said on Thursday afternoon that Lawrie's extended look at second base is over for now, and he will assume a regular spot at third.

The move comes after eight games of uncertainty about where Lawrie would fit into the Blue Jays' lineup. He received six starts at second and two at third base, as Toronto attempted to increase its roster flexibility and evaluate its options moving forward.

"I talked to him today, and he said he's fine anywhere," manager John Gibbons said. "'I'll play anywhere, wherever the team needs.' That was his answer. We don't want to get in the habit of moving you around, but it might help your flexibility down the road. He said, 'whatever you want to do.'"

The decision to keep Lawrie at third base doesn't mean that the Blue Jays have completely abandoned the idea of moving him in the future. The line of thinking is that Toronto is at least relatively comfortable with his work at second base, and a full workload during Spring Training would help ease a transition.

But there was some downside to Lawrie making that transition during the middle of the season. Currently, he's a better defender at third than second, and the Blue Jays don't have internal candidates that would justify a full-time move.

That could change during the offseason, when general manager Alex Anthopoulos attempts to upgrade his roster. Anthopoulos will have plenty of options at his disposal, but for now, the Blue Jays will leave Lawrie where he feels most comfortable and give him an opportunity to put more focus on his work at the plate.

That came as welcome news to Lawrie, who said he doesn't care what position he plays but would prefer to stick with one spot as opposed to moving back and forth.

"I feel fine over there at second base. It's not a question of whether I'm uncomfortable," Lawrie said. "I'm not uncomfortable over there at all. It's about getting reps and being able to go over there and consistently play.

"I've never been a utility guy. I've never bounced around from here, to here, to here and back. So if I get a chance to play in a spot that I'm good at, I'd like to play that spot. If it helps the team out, that's what I'm here to do."

'Pen carrying heavy load, showing some wear

TORONTO -- The Blue Jays' bullpen is starting to show some signs of wear and tear after easily being the club's biggest strength through the first 100 games of the season.

Toronto's relievers entered play on Thursday night having allowed 18 earned runs over their past 13 1/3 innings. One reason for the recent struggles is that right-hander Josh Johnson recorded just six outs during his start on Monday night, and the bullpen has been running on fumes ever since.

That has been an ongoing concern for most of the season, as Toronto's relievers rank first in the Major Leagues with 356 1/3 innings pitched. The workload did appear to have an impact on left-hander Juan Perez, who surrendered five runs in one inning on Wednesday night, his third outing in Toronto's past four games.

"You figure sooner or later, he was going to give up something," manager John Gibbons said of Perez, who hadn't surrendered an earned run in 22 innings before Wednesday. "You can't argue with what he's done, how good he has been."

Johnson was available to pitch an inning out of the bullpen during Wednesday's series finale against the Dodgers, but things should be back to normal after starter Esmil Rogers recorded seven strong innings in the loss.

For the bullpen to remain stable, there's no question that the starting rotation will have to pick up some of the slack. The Blue Jays' rotation has thrown the second fewest number of innings in the Major Leagues this season with 548 1/3. The only team to receive less from their starters is the Twins, with 534 1/3 innings.

"We should be fine tonight, but we needed [Mark] Buehrle to throw some innings," Gibbons said prior to Thursday's matchup against the Astros.

Gregor Chisholm is a reporter for MLB.com. Read his blog, North of the Border, and follow him on Twitter @gregorMLB. This story was not subject to the approval of Major League Baseball or its clubs.