Going the other way, from closer to starter, is a far less frequent event.
This season, however, two players who were closers last season -- Adam Wainwright with St. Louis and Boston's Jonathan Papelbon -- and a third who was a setup man last year after closing four previous seasons, St. Louis' Braden Looper, will be trying to move to the rotation.
History suggests the Cardinals are gambling by moving two pitchers with limited starting experience to the rotation. It happens, but not frequently.
Looper hasn't made a start in 572 career Major League games. All 53 of Wainwright's appearances have been in relief, but as Cardinals manager Tony La Russa pointed out, Wainwright was a starter in the Minor Leagues. Both have the prerequisites to meet the challenge, according to La Russa.
"You need to have command of at least three pitches so you can go through the lineup several times," La Russa said. "It's not the sprint that relieving is. I think emotionally that gets into your fatigue factor."
Injuries can be another factor, especially for a veteran pitcher who has spent his career working out of the bullpen.
That's what happened to former Major League pitcher Rick Aguilera.
Aguilera began his career as a starter in 1985 before switching to the bullpen in 1989. From 1990-95 Aguilera averaged 33 saves per year. The Twins made Aguilera a starter in 1996, and the then 34-year-old went 8-6 in 19 starts due to injuries. The experiment was scrapped and Aguilera returned to the bullpen in 1997.
Others have enjoyed success after making the move to the rotation.
Derek Lowe switched from closer to the rotation without a hitch in 2002.
Lowe, an All-Star closer in 2000, went 21-8 and made the All-Star team in 2002 as a member of Boston's rotation. Lowe saved 42 games in 2000 and 24 in 2001 before moving to the rotation. He is 80-50 in the five years since he became a starter.
Atlanta's John Smoltz spent the first 12 years of his career as a starter before moving to closer for a very successful four-year stint during 2001-04. The seven-time All-Star is 30-16 and has pitched 461 2/3 innings in the two seasons since returning to the starter role.
One of the reasons La Russa is confident Looper can make the switch is St. Louis pitching coach Dave Duncan, who came up with the idea late last season.
"Dunc's mentioning it is enough for all of us, he's that kind of thinker," La Russa said. "I think as far as what he can throw, 100-something pitches in 35 [starts]? [There's] no doubt. I mean he's really strong.
"The biggest part is that we have an outstanding pitching coach, and he's the guy that dreamed it up. If Dunc likes it then it's a got a real chance of working. It's definitely different, no doubt about it."
Looper warmed to the idea when first approached by the Cardinals about the switch, and once he was told it was going to happen, the right-hander simply tweaked his offseason workout regimen.
"The preparations are different. You're preparing more for a marathon than a sprint," he said. "It's still pitching, it's just once every five days instead of an inning or two for two, three games in a row."
Looper has the repertoire to be a successful starter, and with a very good team behind him, he would seem to be in an excellent situation for the transition to work.
"He's got three pitches now, fastball, breaking ball, something softer," La Russa said. "Dunc is into it. It's going to be fun to watch. If it really works out, it's going to be a huge plus for us. If it doesn't ..."
Cardinals fans remember Wainwright and his knee-buckling curveball closing games in the playoffs last year. He was the pitcher who recorded the final out in all three postseason series. But with Isringhausen apparently healthy after last fall's hip surgery and the free agent losses of Jeff Suppan, Jeff Weaver and Jason Marquis, the 25-year-old right-hander will be taking his bender to the St. Louis rotation.
"It's fine by me," Wainwright said. "I'm excited about it. I was glad to help out any way I could. Last year they needed me [to close], and this time they want me to start, so that's what I'm going to do."
Wainwright doesn't foresee any problems making the switch back to starter.
"I've had more experience [starting than closing]," he said. "It might be different if this were the middle of the season, but it's not."
Papelbon has better stuff and more experience than Wainwright, though he hasn't made any starts in almost two years. His other 73 Major League appearances were all in relief. The Red Sox want Papelbon to start to lessen the strain on his shoulder. Pitching every fifth day instead of every day or so is expected to accomplish that goal.
As Lowe did five years ago, the Red Sox are optimistic Papelbon will make the transition seamlessly.
"The reason he went into this rotation is because we're trying to protect him to an extent," Boston manager Terry Francona said. "He doesn't have to go 200 innings for us to consider it a success. I think that's a good way to put it. We're going to keep an eye on him. We're aware of what happened last year. We want to keep this kid healthy. How he pitches, how his shoulder reacts will dictate how much he pitches."
The last time Papelbon started was in 2005, when he made a combined 21 starts at three levels -- 14 starts in Double-A Portland, four in Triple-A Pawtucket and three with the Red Sox. So he's no stranger to starting and has been shaking off the rust in Florida this spring.
"You have to be able to throw other pitches for strikes in any count, and that's the point I want to get at," Papelbon said. "That's the big difference [in starting]. You're having to go deeper into games. You're having to throw more strikes and keep hitters on their toes."
From Isringhausen's unique perspective as one who has made the move the other way and is very familiar with Looper's and Wainwright's repertoires, he doesn't see these moves as a gamble at all.
"You're talking about two guys who have excellent stuff who know how to pitch," Isringhausen said. "And that's what it all boils down to for a pitcher regardless of when he comes into the game."