During one stretch, Thornburg retired 21 consecutive batters over seven outings, Milwaukee's longest such streak since Derrick Turnbow set down 22 in a row during his run as a dominating closer in 2005. Thornburg's streak was finally snapped when the reigning National League MVP, Andrew McCutchen, smacked a double last week in Pittsburgh.
"Who knows?" Brewers manager Ron Roenicke said. "This guy could end up being a closer. I don't know."
Roenicke isn't playing hard to get: He really does not know what the future holds for Thornburg. Neither does general manager Doug Melvin, who, like Roenicke, is keeping an open mind about Thornburg's ultimate role, saying the Brewers will make their call based on organizational need. Ditto, they say, for left-hander Will Smith, who is off to a similarly sensational start in relief.
Thornburg is honest about his personal preference.
"I mean, I honestly feel like throwing 200 innings a year to help your team win baseball games is going to do a little bit more than throwing 80," Thornburg said. "Yeah, ultimately, I'd like to be a starter, just because I could help the team win more with that many innings. But again, the late innings decide a ton of ballgames."
That explains why the Brewers assigned Thornburg to the Opening Day bullpen rather than Triple-A Nashville's starting rotation. He was ticketed for a long relief role, but quickly ascended to late-inning setup duties as a consequence of Thornburg's own dominating stuff, Brandon Kintzler's shoulder injury and Jim Henderson's shaky start.
Roenicke sees a very confident young pitcher.
"His starts last year gave him that," Roenicke said. "I don't know what in the world happened last year at Triple-A [where Thornburg went 0-9 with a 5.79 ERA before the Brewers needed him in Milwaukee], but as soon as he came up here, he was lights out with good stuff."
Thornburg was 3-1 with a 2.03 ERA in his second-half stint with Milwaukee, including 2-1 with a 1.47 ERA in his seven starts. He averaged 92 mph with his fastball, mixing in his excellent curveball and a then-developing changeup. The Mets were impressed enough to ask for Thornburg in a trade for first baseman Ike Davis, but the Brewers refused. Assistant manager Gord Ash said the sides were never close to making a deal.
So far this year, Thornburg's velocity is up (93.9 mph average fastball, according to data from FanGraphs.com), his curveball is still sharp and his changeup is being featured more often.
"You probably see even a little bit more of [the good stuff] in the bullpen because he doesn't have six, seven innings to go," Roenicke said. "He's just coming in for an inning or two and he's letting it go, and he's commanding the ball well, and he has two other great offspeed pitches."
Thornburg is trying to keep it going. With help from Francisco Rodriguez and other more veteran relievers, he is honing a daily routine that includes arm maintenance. Following a growing trend, especially among relievers, Thornburg does not ice his shoulder after pitching in a game. He instead uses methods of increasing blood flow in the joint.
His next hurdle is one all relief pitchers must eventually clear: Pitching three days in a row.
"I'm just trying to remember the things I'm doing well right now and try to stick to those, trying to keep it pretty simple," he said. "I get pumped up in big situations. I like being in close games. Obviously there's a little bit more adrenaline going in. Things have been going well, and you try to ride it out as long as you can."
How far will he ride in relief? Roenicke has been peppered with that question for the past two weeks, as observers wonder whether the Brewers have found a future for Thornburg in the bullpen.
Roenicke has been pushing back.
"The thing is, starters are so hard to find, that where we're going to be in two, three years from now, we may need a starter, and he's a guy we know can do it," Roenicke said. "So it's hard to say where he's going to end up."
He added: "It's nice to have [flexibility]. The one thing we don't know about him -- we know he did a real nice job starting. What we don't know over the course of a year if he can maintain the stuff to get through a season and still be throwing 94, 95 with a nasty curveball, nasty changeup. You don't know how a guy is going to do in a season like that. From what I've seen, he's really good with whatever we do with him."
Thornburg is similarly open-minded.
"Any time you're doing something well, you can see yourself doing something like that," he said. "But I don't think it's anything like, 'I'm good at this, I want to be a reliever.' Heck, what was my ERA as a starter last year? It's one of those things that the toughest thing is bouncing around and not getting used to one thing. I feel like as long as I can get used to one thing -- if I can get used to being a reliever, I can do a really, really good job.
"I'm just trying to thrive in the situation I'm in."