That led the Pirates to place Scahill on the 15-day disabled list Friday with right forearm tightness. Pittsburgh selected the contract of right-hander Deolis Guerra from Triple-A Indianapolis to take Scahill's spot in the bullpen.
Guerra, 26, came to the Pirates as a Minor League free agent in November. He's pitched in parts of 10 Minor League seasons, but never in the Majors.
"It's such a great feeling, just to know that when you work and never put your head down, there's always a chance and there's always something to work for," Guerra said. "And in the end, it pays off."
Once a key piece of the trade that sent Johan Santana to the Mets, Guerra has bounced around in the Minor Leagues since he was 17 years old. Now 26, Guerra has a chance to make his big league debut for the Pirates.
He said he wasn't expecting the call-up, but he was obviously pleased when Indianapolis manager Dean Treanor gave him the news around 8 a.m. ET on Friday.
"I always thought about it. I was having a good season down there, but I wasn't expecting the call today because this ballclub is doing such a great job, especially the bullpen," Guerra said. "I wasn't expecting the call. But it's great."
Guerra was 4-1 with four saves and a 1.23 ERA in 25 games for Indianapolis this season. He has only been charged with a run in three of his 25 appearances this season, and his last 11 Triple-A appearances were scoreless.
"I was able to command my pitches a little bit better this year," he said. "I think that might be the key."
The big right-hander will join a Pirates bullpen that's had to work overtime lately, even with an eight-man relief corps.
Over the last 14 games, Pirates relievers have picked up 49 innings -- but they've done so effectively, posting a combined 1.29 ERA with 40 strikeouts and only eight walks.
To make room for Guerra on the 40-man roster, the Bucs transferred Andrew Lambo, sidelined by plantar fasciitis since May 6, to the 60-day disabled list.
Scahill, 28, is 2-4 with a 2.08 ERA in 26 innings this season. He said Friday afternoon he had no idea how long he'd be out, just that he felt "not that great."