That defense carried him in Denver.
Based on almost every category, the Broncos defense was ranked in the bottom half of the league in 2011.
They were #2 (behind the Steelers) last year and still ended up out of the playoffs early.
Tebow had a little something to do with their success in 2011.
Obviously the Broncos are better off offensively with Manning at the helm but they still had pretty much the same results between the two of them at the end of the year.
Net result with Manning? Unless they win the SB or the AFC this year, zero.