The coach was right on every count, but it was his final reason for the Eagles' record-setting offensive performance that highlighted his ability to dissect an opponent better than almost all of his peers.
"Good offensive line - healthy offensive line," he said. "Those guys played virtually every snap."
It's impossible to know exactly how much that particular fact played in the offensive revolution that Kelly brought to Philadelphia a year ago. But it's safe to assume the coach's rookie season would not have been nearly as successful if he had the same injury problems that plagued Andy Reid's linemen in his final season.
"Continuity among the offensive line is always important," center Jason Kelce said after Thursday's practice with the Patriots. "There is so much communication that happens and there is so much that you are reliant upon the next person that having somebody else in there, even if they are a better individual player, it might not be the best for the unit."
The health of the Eagles' offensive line in 2013 was extraordinary. The quintet of left tackle Jason Peters, left guard Evan Mathis, Kelce, right guard Todd Herremans, and right tackle Lane Johnson started every game together. They were also on the field for a combined 5,426 of the team's 5,520 offensive plays, or 98.3 percent.
"That's rare, but it is a credit to the players involved," offensive coordinator Pat Shurmur said. "I think they did a good job with their training. They prepared themselves physically well each week."
It was the third time in the 21st century that the Eagles' offensive linemen started every game together. They reached the playoffs in each of those seasons. The offensive linemen started all but one game together in 2001, and the only reason left tackle Tra Thomas did not start the final game in Tampa was because it did not mean anything. The Eagles won 11 games and nearly upset St. Louis in the NFC championship game that season.
"It helps a lot just because you get used to working with your guys together," said Thomas, now an offensive assistant with the Eagles. "It's great for spatial awareness, especially when you face a lot of stunts. You know where your guys are going to be and how to bump stuff off and communicate and work with each other."
The Eagles, of course, already know that things are not going to go as smoothly along the offensive line this season as they did a year ago. Johnson, coming off a solid rookie season, saw to that when he was tagged with a four-game suspension for violating the NFL's drug policy. Journeyman Allen Barbre has been charged with replacing Johnson. He played 89 snaps last season, with most of them coming in place of Peters at left tackle. Now, the Eagles need him to play right tackle.
"He's doing good, especially going over to the right side," Thomas said. "It's always different. It's not as easy as everybody thinks it is to switch sides, but he definitely has taken to it and worked real hard at it."
It's better for Barbre and the Eagles that he has had all of training camp to work with the first-team offense, but it still hurts the depth along the line for at least the first four games. Add the fact that Herremans, Peters, and Mathis are all over 30 and there's reason for the line to be at least as big a concern as the loss of Jackson at wide receiver.
"We were very fortunate last year to have great continuity, but I think the good teams still find ways to mix guys in every once in a while . . . because injuries do happen in the game," Kelce said.
So do suspensions, and that's why the Eagles have been forced to mix in Barbre to start this season. Start adding too many guys to the mix, however, and it is bound to be a recipe for disaster.