Making his third start of the season against Port St. Lucie back on April 19, Blackford felt something was amiss the moment his elbow gave out.
"It was in the fourth inning ... I threw a curveball and felt something weird," he recapped. "Then I threw a fastball and it didn't feel right at all."
Blackford would still manage two starts afterward and would go five innings both times out. But his velocity, normally anywhere from 90 to 94 mph, was down considerably in those outings.
"It was pretty obvious to me, to the coaches, and to the trainers that there was something wrong," the right-hander said.
"I was just trying to battle through it because I wasn't sure exactly what was happening. I tried to rehab it a little for a week and a half. I thought I may have just strained it. ... It was a complete tear."
Blackford is the second member of his immediate family to undergo Tommy John Surgery. His cousin, pitcher Eric Stults, underwent the procedure in 2004 as a member of the Los Angeles Dodgers' farm system.
A season ago with Class-A Peoria, Blackford was 10-9 with a 5.37 ERA in 27 starts. He logged 140 2/3 innings, struck out 70, and walked 63.
The Cubs acquired Blackford along with RHP Angelo Burrows from Atlanta in August, 2005, for OF Todd Hollandsworth.
Blackford was the Braves' 13th round selection in the 2004 draft.