Doug Pederson was the starting quarterback for the Eagles in 1999. He is now the team's head coach. Would Pederson the player recognize the team he has built as the coach? Football is a constantly evolving sport, so there are more than a few things that would have Pederson the player scratching his head.

Pederson lined up under center most of the time. The player directly behind him was fullback Kevin Turner. Think about how those elements have changed. Quarterbacks now are primarily in the shotgun. Lining up under center is something you mix in to keep defenses off balance.

As for a fullback, the Eagles don't have one. They aren't alone in that regard. The base formation in the NFL is now three wide receivers, one tight end, and one running back. There are some teams that still keep a fullback around, but those players spend more time on special teams than on offense.

Defenses have had to respond so that means playing three cornerbacks most of the time. Gone are the days of seeing all three linebackers on the field at the same time for a majority of the game. Offensive coaches focus on the passing game so defensive coaches have to focus on stopping the passing game.

The NFL has been a passing league for a while. It took longer for the passing game to become dominant at lower levels of football. The Air Raid offense has now taken over high school and college football. When I was a kid, Oklahoma threw a handful of passes a game. There were times when they might not throw at all. In the last two seasons, OU quarterbacks combined for almost 9,000 yards passing. Think about what an extreme shift that is.

NFL teams are now passing more than ever. Football has really changed in the past 20 years. In 1999, Duce Staley ran the ball 325 times. The Eagles didn't have many weapons, but the plan was still built around feeding the ball to a workhorse back. In Pederson's tenure as head coach, no running back has even had 175 carries in a season. Not only do you throw more, you spread the ball around in the running game.

Positional requirements have changed. Running backs need to be skilled pass-catchers. They used to just catch screen passes and other short throws. They need to run good routes and be able to get open down the field. The running back might shift to the slot or even out wide. You need to move players around to try and create favorable matchups.

That puts more pressure than ever on linebackers to be able to cover. Think about what you've seen from the Eagles in recent years. They drafted Nathan Gerry, a safety from Nebraska, and moved him to linebacker. They signed Kamu Grugier-Hill, whose college defensive coordinator thought was an NFL safety, and put him at linebacker. Both guys have good cover skills. The team signed free agents Paul Worrilow and L.J. Fort. Both linebackers run well and are better in coverage than against the run.

In order to find safeties with good cover skills, the Eagles have looked for cornerbacks to move inside. Avonte Maddox played corner in college and saw some time at safety last season. Everyone in the back seven must be able to cover.