Thornburg was 1-0 with a 0.00 ERA in two big league relief appearances this season, but returned to Nashville with a 0-7, 6.75 mark waiting for him there.
"I know they say the numbers aren't the true picture of what he's doing there, but you still look at that as a player," Roenicke said. "You're still seeing a six-point-whatever ERA. So coming up here and pitching well, especially yesterday, the two innings and getting out of a jam, I can't imagine him not going back and having confidence in what he's doing. He had a great curveball yesterday, his fastball was explosive. I look up there and I see 95 [mph]. And we're not even counting the change-up.
"How can he not go down and pitch well in Triple-A?"
Thornburg saw the roster move coming.
"Things haven't been going my way down there [in the Minors]," he said. "The soft-hit balls are hits, the hard-hit balls are hits. I was fortunate to come up here and have things go my way a little bit. I think for the most part, I was happy to get in a game that was close up here, where you can get a little adrenaline pumping and get locked in."
Adam McCalvy is a reporter for MLB.com. Read his blog, Brew Beat, and follow him on Twitter at @AdamMcCalvy. This story was not subject to the approval of Major League Baseball or its clubs.