London – When it comes to the Vikings quarterback position, they're like a former athlete. The older they get, the better they used to be.

There are few witnesses around to testify to this, but once upon a time the Vikings were a model of stability at the game's most important position. Fran Tarkenton was the first long-term quarterback in franchise history. After he was traded away, the team tried Joe Kapp for a few years, then eventually brought Tarkenton back.

For almost 30 years, the Vikings relied on four starters: Tarkenton, Kapp, Gary Cuozzo and Tommy Kramer, with Kramer beginning to split time with Wade Wilson late in the '80s.

When Wilson failed to take control of the position, Rich Gannon was given a chance to start 35 games over the course of the 1990, '91 and '92 seasons. That's when the Vikings began a series of constant and sometimes desperate changes that preceded the current intrigue surrounding starter Christian Ponder's mysteriously sore rib and backup Matt Cassel's potential first start in purple.

If Ponder couldn't play on Sunday because of a rib injury nobody mentioned until Wednesday, it wouldn't make for the strangest exchange of Vikings quarterbacks.

In 1992, Gannon was the unquestioned starter and was leading the Vikings to the playoffs. In Week 11, he struggled, and in Week 12, while banged up, he was replaced by Sean Salisbury, a journeyman.

My best sources in the organization at that time told me Gannon was being given a rest so he would be ready for the playoffs. Then Salisbury won a couple of games, and his best friend in the locker room, fellow USC alum Jack Del Rio, began lobbying for Salisbury to keep the job, and so when the Vikings reached the playoffs, Salisbury started over a healthy Gannon.

The Vikings lost 24-7 to a battered Washington team. Gannon left. In 1999, he went to the Pro Bowl in his first year in Oakland. In 2002, he was named NFL MVP. Salisbury would start eight more NFL games and be out of the league by 1997.

Salisbury's failure led to Vikings coach Denny Green desperately seeking quarterbacks. He went from Jim McMahon to Warren Moon to Brad Johnson. Johnson started the first two games in 1998 with a loaded team, but sprained his ankle in Week 2. Randall Cunningham, who had been laying tile in Las Vegas, replaced him and led the Vikings to the NFC Championship Game.

The Vikings were 2-3 and being shut out at Detroit in 1999 when Green benched Cunningham in favor of another veteran, Jeff George. Asked why, Green said, "No points." George led the Vikings to the playoffs, but wasn't brought back for the 2000 season.

Finally, the Vikings were ready to start a hand-picked, homegrown quarterback. They took Daunte Culpepper in the first round of the 1998 draft. He would be their starter for the next six seasons, but he would suffer a major knee injury in 2005 and lose his job to Brad Johnson — the same Brad Johnson who had lost his job to Cunningham.

New Vikings coach Brad Childress, aware of the franchise's instability at the position, hand-picked Tarvaris Jackson as his prospective franchise quarterback. Jackson would give way to the likes of Kelly Holcomb, Brooks Bollinger and Gus Frerotte, and throw a critical interception returned for a touchdown in a playoff loss to Philadelphia in 2008, before the Vikings signed Brett Favre.

Favre eventually gave way to Donovan McNabb, who yielded to Ponder, who played so poorly in the first three weeks of this season that the Vikings are considering starting Cassel on Sunday.

Since 1989, the Vikings have had 20 quarterbacks start at least two games. Ten of them were veteran free agents. Cassel could make it 21 and 11. If Ponder is benched because of a rib injury he seemed unaware of, this will hardly become the most dramatic quarterback change in Vikings history.

It will merely be the strangest and most passive-aggressive quarterback decision the Vikings have made since Gannon was benched because of a similarly invisible injury.

Jim Souhan can be heard weekdays at noon and Sundays from 10 to noon on 1500 ESPN. His Twitter name is @SouhanStrib. • jsouhan@startribune.com