Favre had a bunch of not great years during his time in GB. Not sure you can say he was at a pro bowl level for 17 years there.
How many is a bunch?
Probably half of them, to be honest. Of his 17 seasons in Green Bay, he had a passer rating under 90 in 8 of them. For sake of comparison, there were 13 starting quarterbacks with passer ratings over 90 in 2011, including such first-ballot Hall of Famers as David Garrard, Matt Cassel and Joe Flacc

n the flip side, Favre's passer rating for a season never cracked 100 in 17 years in Green Bay. Four quarterbacks did this in 2011 alone.
Favre also never rushed for more than 40 yards in a season- a secondary benefit provided by many quarterbacks to varying degrees every season.
He may be the most overrated athlete in American sports history.
Only 11 QBs with more than 1500 career attempts have a career QB rating of greater than 90. 8 of those 11 are active today (Kurt Warner would have been #9). As ive said in other threads, comparing passer ratings from even the 90's to those of today is ridiculous and incomparable, and even if you do the ol' Gunslinger is still #17 of all-time at 86.1 of all-time (right behind Carson Palmer at #15 @86.7, lol @ qb rating inflation)But to also put that into perspective, Troy Aikman's career QB rating was 82.7, Dan Marino 85.7, Jim Kelly 83.2.
To your point about "cracking 100", he did break 100 (107 actually) in 2009, and he came in at 99.5 in 1995, which to me is far more impressive than the 107 in 2009. I should also point out that only 1 QB has a career average over 100, none other than Aaron Rodgers at 100.3. Next closest are Steve Young and Pihiilip Rivers at 95.7. its all about the west coast offense really and its inflationary effect upon QB ratings.
Im no vikings or Green Bay fan, but you can't deny the guy has put up incredible numbers over an unprecedented period of time and attempts.