A.J. Burnett cannot put much pressure on his right leg, the result of what he called a grade 1 tear in his calf that had him in a walking boot Friday afternoon.
Burnett, who went on the 15-day disabled list Thursday -- retroactive to Sunday -- said he hurt the calf during his workout routine.
"I was just doing my normal running," Burnett said. "Freak thing. I kind of wish I would have done it goofing off. I was just doing my normal stuff. I went to slow down, decelerate. I felt the pop, tug, pull, whatever you call it."
Burnett said the trainers had not given him a prognosis yet.
"Hopefully I can just get back sooner or later and not turn it into a six-week thing, take my time and keep it a two-week thing," he said.
A grade 1 strain is the least severe form of the injury, but Burnett said it was troublesome.
"I'm getting treatment on it all day," he said. "All day [Thursday], all day [Friday]. I just got to stay off of it. Any time I bend the ankle either way, it aggravates it."
Burnett, the Pirates' opening day starter, ranked third in the National League in strikeouts and eighth in innings pitched before Friday. He had a 3.12 ERA in 891/3 innings pitched, and in his most recent start June 8 he went 81/3 innings.
"It had nothing to do with his last outing," manager Clint Hurdle said. "It's just one of those freak accidents or freak incidents that take place."
"I got a history of getting hurt not doing anything on the field," Burnett joked.
Call-up for Cumpton
Brandon Cumpton was charting pitches in the stands Thursday night for Class AAA Indianapolis, oblivious to Burnett's injury or the Pirates' need for a starter today. Only after he returned to the clubhouse did he learn he was to join the Pirates and start today against the Los Angeles Dodgers.
"I'm just awed right now," he said. "I don't know what to think, being around all these guys right now. I'm sure it will set in later on."
Cumpton, a 24-year-old right-hander, is on the taxi squad. The Pirates have to add him to the active and 40-man rosters by 1 p.m., meaning they will need corresponding roster moves to do so.
"I feel like [I have] been pretty consistent this year," Cumpton said. "I try to go for six, seven innings and get deep so I can turn it over to the bullpen."
The Pirates drafted Cumpton out of Georgia Tech in the ninth round in 2010. He spent all of 2012 in Class AA Altoona, where he had a 3.84 ERA and 88 strikeouts in 1521/3 innings.
He made two starts for Altoona this year before being promoted to Indianapolis. He had a 3.31 ERA in 11 games, 10 starts, with Indianapolis this season.
He has a career rate of 5.8 strikeouts per nine innings in the minors, but doesn't walk many batters or allow many home runs.
"Strike-thrower, moves the ball both sides of the plate, spins it, changes speeds," Hurdle said.
"He's a competitor."
Marte out again
Left fielder Starling Marte did not start for the second consecutive game because of pain in his ribs.
Hurdle said Marte hurt himself sliding head-first into a base.
Bill Brink: email@example.com and Twitter @BrinkPG.