You know the story.

Pro Bowl quarterback gets traded by his long-time employers to a division rival. Quarterback gets benched late in the season, is shipped out for a sixth-round draft choice and takes a 60 percent pay cut to play for near-backup money. Debuting for his third team in three years, quarterback throws for 39 yards on an otherwise record-setting passing weekend in the NFL.

Donovan McNabb threw for just 39 yards in the Vikings' opener. Matt A. Brown/Icon SMI

The pattern doesn't look good for Donovan McNabb, whom the Minnesota Vikings acquired this summer to provide a short-term competitive jump while rookie Christian Ponder spends some development time on the sideline. Speaking to reporters Wednesday, McNabb admitted that "from the start of this, there can be a lot of assumptions." But he suggested that writing him off after one unproductive week would be a mistake.

"A lot of times we make too much of one particular game," McNabb said, "where all of a sudden one person looks great and the other guy, he doesn't have it. And as the season goes on, the guy that they felt looked great in the first game, you don't hear about any more. And the team that maybe started out a little slow and continued to progress, those are the teams that you talk about later. That's one thing that I've learned in my 13 years."

In truth, anyone who watched the Vikings' 24-17 loss to the San Diego Chargers knows McNabb deserves but a portion of the blame for Minnesota's anemic passing results. The Chargers' pass rush broke free a number of times, and as we discussed earlier this week, the Vikings called a run on about 80 percent of their first-down plays.

It's no secret that tailback Adrian Peterson is the Vikings' best player, but McNabb insisted that the offense will "by no means" be predictable and hinted there is much more coming on the proverbial conveyor belt.

"I mean everyone expects us to hand the ball off to Adrian," McNabb said. "But there are plays in this offense and things that we can do, and things that we will do, that will begin to answer a lot of the questions that teams might have."

It would be unfair for everyone involved to start drawing conclusions about McNabb. He was a pretty good quarterback as recently as 2009, and the blame for his performance last season for the Washington Redskins has been debated around the NFL.

But I'm also reminded of our discussions on this blog about former Chicago Bears defensive tackle Tommie Harris, whose production dipped dramatically after his 2007 Pro Bowl season. As the Bears waited for him to return to form over the next three seasons, it became clear: The longer a player moves away from success, the less likely he is to regain it.