The problem is that Favre did audible so often at the line of scrimmage it's pretty much impossible to know now how often those crazy interceptions were attributable to flaws in playcalling, miscommunication between the quarterback and receivers, or simply improvisations gone awry.
If the problem was the first factor -- coaches calling for deep passes when only a few yards were needed -- then that does absolve the quarterback of some responsibility and points to coaching miscues.
If it was the second, that would absolve the quarterback of responsibility for many of the turnovers. However, I would still ask, since Favre is often lauded as being the best quarterback in history at reading and reacting to defenses, shouldn't he have been able to read and react to defensive mismatches resulting from these miscommunications? Yes, I know there are many timing plays in which the quarterback throws to where the receiver is supposed to be, but one would think that there would be some times in which it was obvious the receiver was running the wrong way and the quarterback could pull it in.
If it was the third -- which, based on the number of gambles Favre made that just happened to work out, I'm convinced a large number of them were -- then I think his frequent lack of discipline screwed the team at times. I'd love to see a statistical analysis done of how often Favre's improvisations and play changes actually benefited the team and how often they resulted in no gain or backfired. Unfortunately, because (to my knowledge) no permanent record of the actual playcalls exists, that is probably impossible.
It would be awesome if such a record were maintained, though. Even purely for curiosity's sake, it would be interesting to note how often Favre (or any NFL quarterback, for that matter) changed the plays at the line, and what proportion of plays were executed as called.