Philadelphia wound up running just 1,054 plays last year, which placed the Eagles behind 12 other teams. Does that mean the stories about Kelly and the team’s fast tempo were overblown? No. One extenuating factor was that Foles led the NFL in ANY/A and LeSean McCoy averaged 5.1 yards per carry while leading the league in rushing yards. Philadelphia finished 1st in the NFL in plays of 20+ yards by an astonishing margin: the Eagles had 99 such plays, with the Broncos second with 77. The Eagles also had the most 30+ yard plays and 40+ yards plays, and well, you get the point: it’s hard to accumulate plays when you know, you keep running into the end zone.

But Philadelphia ranked dead last in average minutes per drive according to Pro-Football-Reference.com. The Eagles also ranked 1st in the majority of the Pace Stats on Football Outsiders, including seconds per play, seconds per play in the first half, seconds per play in close games, and seconds per play in neutral situations.

Philadelphia led the NFL in yards per play (6.33) and 32nd in number of seconds between plays. I’d say that’s a pretty ringing endorsement for Chip Kelly’s offense.

I'm maybe missing something here, but surely time of possession is less important than plays run or points scored?

And I don't buy the argument that a fast paced offense tires out its own defence for two reasons. Firstly, it's the opposition defence that has to cope with the fast offense so it should be the one to wear down. Secondly, our defence is still facing the same number of plays and can reduce that by getting a stop.

True.

The defense can reduce the amount of time it is on the field by getting stops and getting the heck off of it. We were weak last year and didn't do that enough, although there was some improvement from mid year on.

However, our ultra efficient offense does result in less TOP, all things considered equal and will result in more time our D is on the field, maybe to the tune of four minutes per game or so.

However, our D should not be as tired as the opposing D because of pace.

Lastly, if our O is so good as to get a lead, it can dictate the play selection as passes by the opposition which makes it easier to defend.

The defense has less time to recover when the offense scores quickly. If it also makes stops, they are on and off the field rapidly. It's more like running wind sprints than a marathon. This is likely where Chip's sports science is intended to pay dividends.