During his time with the Raiders the Broncos have only won 8 games (8-17) so its not like these 3 wins were against a good team.

Of the major sports I think the NFL is the most dependent on coaching. During the 80s and 90s the league was pretty much dominated by 4 coaches:

• Bill Walsh
• Joe Gibbs
• Jimmy Johnson
• Bill Parcells

Whereas the AFC had the better coaches the previous decades like:

• Noll
• Shula (he continued to coach into the 90s but he was mostly ahead of his peers in the 70s.