Even with the Broncos off to a 5-0 start in 2015, Peyton Manning has sunk to an all-time low.

The 39-year-old quarterback's play has been scrutinized since the season began, but it was a comparison to a former Broncos quarterback that dropped the bombshell on Manning, thanks to NFL.com.

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"Manning's offense is averaging 1.7 touchdowns per 60 minutes this season, a dramatic drop off from 3.4 in 2014 and 4.4 in the record-breaking 2013 season," NFL.com reported. "In fact, the Tim Tebow-led 2011 offense averaged 2.0 touchdowns per game."

Tebow took over as the Broncos' starting quarterback for the last 11 games of 2011 and threw for 1,729 yards with 12 touchdowns, six interceptions and a completion percentage of 46.5.

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But Tebow also had 660 rushing yards with six TDs.

Manning is one of four starting quarterbacks to throw more interceptions (seven) than touchdown passes this season.

He has failed to lead the Broncos to an offensive touchdown twice this season, during Week 1 and Week 5. The last time a Manning-led offense failed to score a touchdown in a game was 2003, NFL.com reported.

"He ranks 22nd in QBR, 25th in passer rating and 25th in Pro Football Focus' quarterback grades," according to NFL.com. "Prior to Week 5, Football Outsiders' efficiency ratings placed Manning 32nd out of 34 qualifying quarterbacks and ranked the Broncos' offense 30th out of 32."

Peyton's season adds to the mystery behind NFL teams steadfast refusal to sign Tebow as a backup. The Broncos still are winning with subpar play from their quarterback, and the Cowboys current starter, Brandon Weeden, has lost the last 11 games he has started.

Tebow couldn't be any worse, unless a team was to start him in 12 games and he lost all of them. But he can't even make a roster, let alone start any games.

And for all his success, Manning's record in the postseason (11-13, .458) is percentage points worse than that of Tebow (1-1, .500).

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