PHILADELPHIA -- Chip Kelly still had the upbeat demeanor of the successful salesman who truly believes in his product. And that’s as it should be. It wouldn’t say much about the product if Kelly’s confidence was shaken by two lost football games -- even if they were at home, against teams the Philadelphia Eagles were favored to beat.

“I think you draw on the positives,” Kelly said Friday afternoon. “You know, what did you do well? And then look at what correctable mistakes occurred in the game and address them. That's what I talked about in the locker room after the game with our guys.”

But Kelly’s belief in what he’s selling isn’t the issue. It’s whether his players believe in it, too. We talked about that in the affirmative after the Eagles’ breathtaking debut at Washington on Sept. 9. If actual on-field success had the players buying in, what effect do two bad losses have on them?

Cover the Eagles, and Philadelphia sports in general, long enough and you become a connoisseur of losing locker rooms. After Thursday’s loss to Andy Reid and the Kansas City Chiefs, the Eagles were a notch or two below the standard postgame disappointment. Most of the players cleared out very quickly, leaving one writer to wonder aloud, “When did this become the Phillies clubhouse?”

Asked to describe the mood, cornerback Cary Williams said, “Somber.”

It is understandable. The Eagles lost 11 of their last 12 games in 2012. That is just an emotional pounding when you’re as competitive as professional athletes are by definition. This team embraced Kelly’s fresh approach -- from the blaring music to the smoothies, to the up-tempo offense, to the win-the-day culture -- because it very much wanted to be led out of the NFL valley of despair.

So the same thing that made the Eagles so giddy after the Washington game made them so despondent after a second, even more 2012-like loss in four nights.

Guard Todd Herremans, who is normally expansive in his willingness to share his knowledge of the game, was reduced to monosyllables. Center Jason Kelce, one of the smartest players on the team, was forced to explain how he snapped the ball into thin air, creating a turnover, and later failed to snap it at all when the rest of the team jumped on the proper snap count.

When it worked at Oregon -- and certainly when it worked against Washington and San Diego -- Kelly’s offense requires and inspires a certain swagger. It is the defense that wears down, loses focus and makes mistakes. On Thursday, that happened to the Eagles' offense: six sacks, five turnovers, just 16 points.

It doesn’t help that Kelly has given his players other reasons to doubt him. He says time of possession is meaningless, but the players now know what it physically feels like to be on the wrong side of a 2-to-1 disparity. He says his methods guarantee the Eagles will be fresher than their opposition, but their bodies tell them otherwise.

Kelly’s admitted ignorance of a timeout rule in the San Diego game didn’t help. Neither did the gimmicky two-point conversion play that failed Thursday night and sapped the Eagles’ hard-earned momentum.

It would be going way too far to suggest that Kelly has lost his team. But it is fair to say that is what is at stake after two bad losses in five days. Kelly is facing his first real test as an NFL head coach.

The schedule does him no favors. He gave his players off until Tuesday. They return and begin preparing for a game against Peyton Manning and the Broncos in Denver. They play the Giants, also on the road, the week after that.

In a situation like this, players look to the head coach. They want to see how he is reacting and whether he has any answers. That same flat-line demeanor that annoyed some fans about Reid was intended to reassure his players. In his best years, Reid backed that up by coming up with concrete solutions to on-field problems.

Kelly has the demeanor part right. His unwavering confidence in what he’s selling is crucial right now. It has worked for him in the past. It’s just that he might have to tweak the product a little bit to appeal to this slightly older, more affluent demographic.