ANAHEIM, CALIF. -Tom Kelly used to say that you didn't need a supercomputer or a lifetime in baseball to figure out how a pitcher was faring. Kelly's measure: "Just listen to the sound the bat makes."

Kelly would have enjoyed Brian Duensing's brief appearance on Tuesday night more than a thousand symphonies.

Duensing, the Twins' versatile lefty, came in with a runner on second and two outs in the seventh, protecting a 5-3 lead at Angels Stadium. He faced Hideki Matsui, who had homered off the Twins' other lefthanded reliever, Jose Mijares, on Monday night.

On the third pitch of the at-bat, Duensing busted Matsui inside. Matsui's bat made a sickly snapping sound as the ball rolled to second for the key out of the Twins' 5-3 victory.

That quickly, Duensing indicated that he could become one of the Twins' most valuable pitchers.

Consider his last two appearances in meaningful Twins games:

On Oct. 7, 2009, he started Game 1 of the playoffs in Yankee Stadium. On Tuesday, he retired a formidable veteran slugger who had beaten the Twins' lefty specialist the night before.

Suddenly Duensing looks like he could challenge Mijares as the Twins' go-to short lefty, even as he remains their first choice to join the rotation should a current starter falter or get hurt. He's also their best long reliever, although the Twins would probably opt to use Alex Burnett in that role to keep Duensing in reserve for the late innings.

"It's interesting, because we've got to make sure Mijares gets going or Duensing slides into that role," Twins manager Ron Gardenhire said. "With Mijares, we have all the confidence in the world that he's going to start throwing the ball well, but if he doesn't, we don't have to worry about that.

"Duens can go either way. He's stretched out enough that he can handle the long role, but you hate burning him up that way. He's too valuable, being able to come in and get outs like that. And he's our guy if anything ever happens in our rotation, he comes right in there. He's really, really valuable."

As often as managers and general managers preach patience during a 162-game season, Duensing is proof that assignments and careers can swerve faster than a vintage Francisco Liriano slider.

Duensing made the Opening Day roster in 2009, but he was sent to the minors on April 14 while the regrettable Phil Humber became the Twins' long reliever.

When you get demoted in favor of Phil Humber, your career is in jeopardy.

But Duensing earned a recall in July and made his first big-league start on July 29. He proved himself to be a smart, competitive starter, finishing the season 5-2 with a 3.64 ERA and helping the Twins surge into the playoffs.

He just didn't expect to start Game 1 in Yankee Stadium. He recalls his conversation with pitching coach Rick Anderson last October this way:

"I threw the game against Kansas City that last series in the Metrodome, and Andy came up to me afterwards and said, "We want to get you some work, you're going to start on Wednesday.' I said, 'OK, no big deal.'

"I sat down next to Kevin Slowey. He said, 'What did Andy say?' I said, 'He told me I'm starting on Wednesday.' Kevin said, 'Oh, OK, Game 1.'

"I said, 'Oh, crap.' "

Duensing gave up five runs in 4 2/3 nnings in Game 1 while becoming the third Twins rookie ever to start a postseason game.

"To me, it was exciting," he said. "It happened so fast, it took a little while even after the season was over for me to grab hold of what had happened.

"I hate the fact that we lost, but the whole experience was surreal. It was a good time."

Tuesday, Duensing threw three pitches, then heard Anderson say: "Good job, you're out of the game."

Duensing's reaction: "Sweet, I'll take it."

If he keeps breaking bats, he may take someone's job.

Jim Souhan can be heard at 10-noon Sunday on AM-1500. His Twitter name is SouhanStrib. • jsouhan@startribune.com