The shelf life of an average NFL career is so short that players don't typically get two stints with the same team.

Sage Rosenfels has done that twice.

The veteran quarterback walked out of the Vikings locker room before the 2010 season and returned last week when the team claimed him off waivers after he was released by the Miami Dolphins.

Rosenfels has played for five teams -- including the Dolphins and Vikings twice -- in his 11 seasons so he knows you never say never in the NFL, no matter how unlikely a scenario might sound at the time.

"I think generally you sort of hope that if you go to a new team you can play there for a long time," he said. "You just never know in this league. So many weird things happen with injuries and coaching moves and those types of things that you really can't count anything out."

Rosenfels has witnessed his share of oddities, a lot of it after the Vikings traded for him in 2009. The original plan was for Rosenfels and Tarvaris Jackson to compete for the starting job until a certain gray-haired quarterback came out of retirement. Rosenfels served as the No. 3 quarterback as Brett Favre led the team to the NFC title game that season.

Rosenfels clearly outplayed Jackson in the 2010 preseason, but Brad Childress got his way and traded Rosenfels to the New York Giants before the season.

Childress staked his reputation and job on Jackson and never connected with Rosenfels, who had vice president of player personnel Rick Spielman in his corner. Rosenfels' first go-around didn't work out the way he envisioned, but he didn't torch the bridge when he left town to become Eli Manning's backup in New York.

"I have no issues," he said this week. "I was hoping to compete with Tarvaris that year and it didn't end up working out that way. I have no problems with the year I was here. Obviously there's been some drama and turmoil since I left, but it was one of the most memorable years of my career that year."

He can't say the same about this season, at least not memorable in a positive way. Rosenfels expected to serve as Manning's backup again, but he came down with strep throat in training camp. That developed into a blood infection, which caused back problems. The Giants placed him on injured reserve while he recovered and then released him in early October.

Rosenfels signed with the Dolphins but became ill almost immediately and was placed on the reserve/non-football illness list after being diagnosed with mononucleosis. He took five weeks to recover and then was placed on waivers by Miami last week. The Vikings claimed him after jettisoning Donovan McNabb.

Rosenfels didn't need a GPS to find Winter Park, but the circumstances couldn't be any different in his return. The Vikings went 12-4 and could smell the Super Bowl in his first stint. Now, they're 2-10 and an unmitigated mess.

He's also not coming in to compete for the starting job. He's here to run the scout team and lend a veteran voice and perspective to rookie Christian Ponder. But for how long?

Rosenfels' contract expires at the end of the season. He turns 34 in March and has not attempted a pass since the 2008 season. But he has a strong ally in Spielman and he shouldn't have a lot of wear and tear on his body. The thought of him returning next season is not implausible. Rosenfels deflected any such speculation, except to say he hopes to play several more years.

"Right now I'm thinking about learning this offense and figuring out what Detroit is doing," he said. "Thinking about next year is really not what NFL players should be doing. You need to worry about this week."

Rosenfels' role could change this week depending on the severity of Ponder's hip injury. Joe Webb will take first-team reps in practice while Ponder gets limited work. Ponder is expected to play against the Lions, but Rosenfels needs to get up to speed quickly just in case.

"Basically what I did this week is I told the coaches the plays that I was comfortable with," he said. "Hopefully next week it's twice as many."

The way this season has gone for the Vikings, Rosenfels could end up as their starter at some point. He's seen some weird things, but that one might take the prize.

Chip Scoggins •