The Eagles won't know by Monday whether they had a successful draft over the weekend. They can't even be sure whether they had a successful draft a year ago.

"Last year's draft has a chance to be really good," general manager Tom Heckert said during a meeting with reporters yesterday.

That would be the draft that produced Brodrick Bunkley, Winston Justice, Chris Gocong, Max Jean-Gilles and Jeremy Bloom, among other players you know as little about today as you did before their rookie seasons started. Right now, 2006 looks like a pretty underwhelming vintage.

There are reasons the 2006 class hasn't matriculated yet - including injury, starters blocking the players' paths, and Bunkley's holdout. But there's something else, too, something that may help explain some of the draft picks the Eagles have missed on in the Andy Reid era.

The Eagles' offense and defense are just really, really complicated.

This idea isn't new. It's come up in the past when a wide receiver would spend two or three training camps as an apprentice before the team quietly gave up on him, or when a veteran free-agent linebacker would come here after playing well elsewhere and disappear in full view.

Heckert acknowledged the difficulty of projecting college players, especially at certain positions, into complicated NFL systems.

"I think the offensive and defensive schemes are getting a lot more complicated," Heckert said. "There are so many pass protections and routes and moving guys out to the slot. A lot of times now, you want guys playing more than one position if they can. A nickel defense for our linebackers is completely different than our regular defense. I think there's a lot more for them to learn, and it's something that they don't do in college. You're really going into it blind to begin with and you have to make an educated guess whether the guy is going to be able to pick it up or not."

That isn't easy. Each team gets a chance to meet with players at the scouting combine, then to bring 30 in for more in-depth visits. Scouts and coaches can call up college coaches and try to get insight into whether players were quick studies or slow learners, whether they worked hard or just showed up.

But there's no way to be sure a particular player will fit into your particular system, coached by your particular coaches, until he's already on your roster.

"We do find mistakes where it's a non-athletic deal," Heckert said. "Was the guy not as intelligent as we thought he was? Was his work ethic not what we thought it was? Maybe we draft guys who don't fit our scheme quite as well as we thought they did."

You look at some recent draft picks who haven't developed into productive starters and you can see the pattern: Jerome McDougle and Billy McMullen from 2003, and Matt Ware from 2004. The jury is out on 2005 picks Mike Patterson, Mike McCoy, Ryan Moats and Sean Considine.

Thing is, there's a reason college systems don't tend to be as complex as NFL systems. College coaches have always dealt with constant turnover. The longest they can have a player on the field is four years. The NCAA limits practice time. Good coaches generally keep it as simple as possible, taking full advantage of the players' athleticism.

Here's the rub. The modern NFL is more like the college game than ever when it comes to roster churn. One thing you heard a lot from this year's Super Bowl teams, the Colts and the Bears, was that their systems were relatively simple, to take advantage of the players' raw talent.

"In our defense, you go after the guy with the ball," Bears middle linebacker Brian Urlacher kept saying. Indeed, the Colts and Bears both played versions of Tony Dungy's "Tampa 2" or "Cover 2" defense.

Reid believes completely in his derivation of the complex West Coast offense (although players did say that coordinator Marty Mornhinweg simplified things when he took over play-calling last season). Jim Johnson's fire-zone defensive scheme isn't merely complex; it has evolved to take advantage of the skills of specific players, such as Brian Dawkins.

The Eagles aren't likely to change. Given their track record, no one is suggesting that they should, really - not when weighed against what may turn out to be one fluky season for the Bears' and Colts' approach.

But all this may help explain why some players take a year or two to be ready to contribute, why some who looked terrific in college and at the combine never play here at all, and why no one will know Monday whether this year's draft, or last year's, was a success.

Contact columnist Phil Sheridan

at 215-854-2844 or psheridan@phillynews.com.

Read his recent work at http://go.philly.com/philsheridan.