What if the Eagles had hired Rob Ryan?

We all know that if the San Diego Chargers had hired Rex Ryan instead of Norv Turner to be their head coach in 2007, they'd have two Super Bowl rings by now. This is headline news today, in large part because Ryan has become a prominent head coach at a time when no one in the NFL can seem to take a joke.

But the hubbub over all of this got me thinking about another Ryan -- Rex's brother, Dallas Cowboys defensive coordinator Rob Ryan, and whether the Philadelphia Eagles might have been better off hiring him as their defensive coordinator last winter instead of promoting offensive line coach Juan Castillo to the position.

Now, up front, let me say that I don't know that this was possible. Rob Ryan was officially hired by the Cowboys 10 days after the Eagles' playoff loss to the Packers, so it's likely his deal with Dallas was done before the Eagles ever knew they'd be firing defensive coordinator Sean McDermott. So this isn't a column that says the Eagles made a mistake by not getting Rob Ryan. I don't know if they ever could have.

But there's a point to be made here about the value and importance of coaching in the NFL, and the difference between the way the Cowboys' defense and the Eagles' defense have played this season helps make it.

Both defenses needed help. Both underachieved in 2010 -- the Cowboys to devastating levels and the Eagles just enough to cost them down the stretch. Both teams needed to overhaul things on the defensive side of the ball, and they went in different directions to do it. The Cowboys believed they had the player personnel in place to have a good defense if they could just get 2009 stars, such as Anthony Spencer and Mike Jenkins, to play the way they'd played in 2009. Add a safety here, a 3-4 defensive end there, promote Sean Lee to starter, and they felt like they weren't far off. What they needed was somebody who could bring it all together, and so they brought in Rob Ryan, who'd coached the Cleveland Browns' defense to respectability in 2009 and 2010 and clearly knew what he was doing.

The Eagles needed to change personnel, so they decided to overhaul everything. Not only did they switch Castillo from offensive line to defensive coordinator, they brought in respected defensive line coach Jim Washburn. They decided they would play a completely different style of defense, built on linemen who get upfield and harass quarterbacks. They went out into the trade and free-agent markets and brought in two new cornerbacks and two new defensive linemen and built it all up from scratch, and they gave all of this responsibility to a guy who'd been coaching the offensive line for the previous 13 years.

The results? Well, the Eagles have struggled, and the scheme and its administration have come under fire. Washburn's "Wide-9" defensive front appeared to leave the Eagles vulnerable to the run through the first five games, especially because they underspent at linebacker and don't have the players at that position to support the hyper-aggressive line in run defense. For some reason, they're playing their new cornerbacks in zone coverage when they've excelled in the past as man-to-man cover guys. Castillo has shown an ability to adjust and fix things during games, but the Eagles' defense often seems unprepared at the start of games, getting run over early by everybody from Steven Jackson to Fred Jackson to Victor Cruz.

There was a lot to bring together here in a short period of time, and they took a big risk by handing that responsibility to a first-year defensive coordinator. The results are mixed. The Eagles rank 14th in the league in total defense as measured by yards allowed per game, but their struggles in the run game prior to last week and their susceptibility to big plays early in games has cost them dearly.

The Cowboys, who were one of the league's worst defenses in 2010, currently rank fifth in the NFL in total defense. Only the Steelers, Bengals, Ravens and Chargers have allowed fewer yards per game. No team has been tougher against the run. And Dallas has played two of the league's highest scoring teams in its past two games. The Cowboys added Abram Elam at safety and Kenyon Coleman at defensive end -- two guys who'd played for Ryan in Cleveland -- and they let Ryan at the holdovers. The result is that guys such as Lee, Jenkins, Spencer and Terence Newman are playing lights-out. The Cowboys eschewed major personnel changes in favor of a new, stronger voice -- an experienced and accomplished defensive coordinator -- and it appears to be paying off. They're 2-3, but most of that is on the late-game failings of the offense. And with the schedule about to soften up, Dallas' improved defense could be a key to a huge second half.

Two different approaches to similar problems. And the year isn't even halfway over yet, so it's too early to say for sure whose solution was the better one. But the early returns indicate that the Cowboys' decision to emphasize coaching as a way of improving on defense was a smart one, and that the risk the Eagles took by underemphasizing it may prove costly.