If his 55-touchdown season and seven-touchdown game are the top of the scale, an A-plus, then what constitutes failure? The 14 sacks in his past 10 games? His poor performance against the blitz?
And how do you judge the whole of his 2014 season, which featured 39 touchdowns? Manning finished fourth in the NFL in passing yardage and second in touchdowns last season. But after 22 touchdown passes and three interceptions in the season's first seven games, Manning had 17 TD passes and 12 interceptions over the last nine games.
The key for Manning is handling the increasing pressure being dialed up by opposing defensive coordinators. Since Week 11 of last season including the playoffs, Manning has completed 49 percent of passes against the blitz, 29th among 35 quarterbacks with 25 attempts. In the season-opening win against the Ravens, he was sacked four times and had a pick-six. All of those miscues came when the team was in a three-wide receiver set, giving him less protection.
Manning is used to running a high-flying offense that produces eye-popping stats. But at 39, he may need to adjust his game, and others’ expectations, to get the protection he needs to succeed.
"It's who he is, everybody always expects perfection," cornerback Chris Harris Jr. said. "He can't just win sometimes. We're a team, and on defense we'll be there for our offense because they've been there for us. We want to win, however that happens we'll just keep moving along."
Consider Manning's past 10 games. The Broncos have won seven of 10, but Manning had his worst Total QBR (52.6) since ESPN started tracking it in 2006. Manning also ranks below the league average in yards per attempt (6.8) and touchdown-to-interception ratio (16-11).
So what has changed?
As a future Hall of Fame quarterback, Manning has always received the ultimate respect from defensive coordinators. They played to limit the damage.
But now defensive coordinators see their chance. Much like the offensive linemen who chased a weak-kneed Dick Butkus to exact revenge for seasons past; they have a boldness in their approach, a challenge.
They are coming after Manning with a template that proved successful last November that has since been copied and pasted on every defensive game plan.
Be aggressive early in the pass rush, especially in the middle of the formation.
Clog the short and intermediate routes.
Leave the holes deep down the sidelines and see if Manning and the Broncos' offense can make you pay.
The Colts made it work in the playoffs, as Manning looked uncomfortable and out of sorts after an early strip sack. The Broncos lost 24-13.
He's been hit in the pocket more as the Broncos have had a variety of issues on the offensive line, issues that were again evident in Sunday's win. So, did the Ravens follow the defensive script?
"I wouldn't say that," Broncos coach Gary Kubiak said. "They played us in various coverages. We saw two-shell safeties, we saw the blitz, we saw a little bit of everything from Baltimore. We saw the kitchen sink, as a matter of fact. I would not say [we saw that defensive script]. You have to adjust to everything."
Broncos receivers say Manning's arm is strong. Demaryius Thomas said the throws have "more zip" than last season. Broncos coaches point to big plays missed by a hair and say if a handful are made, the conversation around Manning is drastically different.
There are likely two adjustments the Broncos can make. They can either find a way to punish defenses deep or run the ball better, which will enable them to eventually punish defenses deep.
They have to put stress on defenses deeper in the intermediate area, which is a throw Manning consistently makes. Denver also has to resist opening the formation, at least until the Broncos prove they can protect Manning better.
Beef up, bulk up and buck up. Manning and the Broncos need to embrace this way of thinking if the Super Bowl is still where everybody wants to go.