What does Tavaris Jackson have that 95 percent of other NFL QBs don't have? If you said sub 4.6 speed, then you are right (Vince Young, Seneca Wallace, Gerrard showed flashes, just to name a few).
Since that is the case, the majority of NFL playbooks, handed down coaching trees, do not factor into their plays that their QB might outrun DL and most linebackers. Now I looked for a while, but could not find any stats for percent of rolling out of pocket and throwing on the run.
Now after continually hearing that TJ was not a good quarterback, I decided to pay more attention on pass plays, rather than zoning out because AP wasn't running it.
Other than noticing that the Viking receiver's dropped it more than acceptable, I noticed that Childress barely ever had a designed play for Jackson to use his legs to create a huge mismatch.
Also, when your offensive leaders legs are among the best in the league at his position, letting him sit in the pocket and pretend to be a pocket passing game manager is lying to yourself, hurting your chances, and not letting him reach his full potential.
Now I'm not saying you should have him get 80+ yards rushing a game, but but if it helps him get out of trouble, set himself up for long runs, and helping him to move offenses horizontally, which can help during the play more than most people think, you will pass for more yards, and probably run for more also.
Another thing, if the Vikes do sign Favre, and Jackson gets in as a situational QB, it will be with the intent to force secondaries back in coverage to help his run as much as the underneath passing routes you can run with Harvin.
So if he is a situational runner with Favre, why not without?