Eagles coach Chip Kelly might be considered a visionary on offense with his uptempo system and unusual formations.

That is not the case on defense where Kelly leaves the schemes to coordinator Bill Davis who must find a way to as he put it conduct “a major overhaul” of a defense that ranked 29th out of 32 teams last season in points allowed.

Davis is changing everything about the Eagles’ defense and he admits there are going to be growing pains.

The Eagles are transitioning from the wide nine they used last season to a 3-4 hybrid. Davis has just five returning starters from that defense in linebackers Trent Cole Mychal Kendricks and DeMeco Ryans safety Nate Allen and defensive lineman Fletcher Cox.

But Cole and Brandon Graham are career defensive ends switching to outside linebacker which means they’ll have to drop into coverage on occasion something they rarely — if at all in Graham’s case — did in the past.

In addition Davis’ job could get much tougher if the uptempo offense that Kelly espouses goes three-and-out often during a game which could wear out the defense.

“I think we’re at the beginning stages of building the defense” Davis said. “Every defense wants to be that feared intimidating defense. I think the foundation is being laid but there is so much work to be done yet.”

There’s nothing unusual about a head coach delegating responsibility to his coordinator.

Kelly’s predecessor Andy Reid relied on longtime defensive coordinator Jim Johnson until Johnson died from skin cancer in 2009. Former Phillies manager Charlie Manuel a noted hitting guru left the pitching staff to pitching coach Rich Dubee.

None of that makes it easier for Davis however. He is the Eagles’ fourth defensive coordinator since Johnson’s death and third since the start of the 2012 season.