Chad Ochocinco, despite his physical talents, was never able to fully grasp the Patriots system.
Since the start of the Bill Belichick era, the New England Patriots have always had a notoriously complex passing playbook, that requires the ultimate chemistry between quarterback and receiver, due to all the different option routes available to the receivers based on the defense that they read.
Whenever a player like Chad Ochocinco or Joey Galloway comes into the fold and can't get a grasp on the offense, the system's complexities are always highlighted. This being said, Doug Farrar of Yahoo!'s Shutdown Corner blog, recently had a very in-depth look into the Patriots option offense from a receiver's perspective, that is certainly worth a read:
O'Shea wasn't kidding. In one Patriots playbook I've seen (the 2004 version), there were 25 different single receiver routes, and that doesn't count all the available options. Nor does it cover where those routes are run in a split on the field, or how the receivers run routes in tandem. There were 17 different two-man route combos in the playbook I saw, and five different three-man route combos. Once you've mastered all that stuff, there's then the matter of the call in any pass play -- the name of the route group that a team decides on any pass play for anywhere from one to five receivers. Add in the protection at the line, and you have the start of what will be an eventual Patriots play call.
One example (diagrammed here): "1 Out Slot ZAC." In this play, the fullback (lined up wide left) runs a 14-yard in, though he should look for an outside release if anyone's cheating up expecting something quick. The halfback reads blitz, hits a run sneak through the A-gap if he's free, and digs sharply to the right. The "X" or iso receiver does a sight adjustment, reads the coverage, and could either come back outside, or loop to the seam, depending again on the coverage. The "Z" receiver motions from right slot, and heads 6 yards upfield, into a four-way option. The "Y" receiver could turn a "chute" route, or he might hook inside.
That's one pass play -- one variation of a subgroup -- in a playbook that would rival the phone book for any large metropolis in overall ginormosity. And there are other ways in which offenses can confuse.
It's a long read, but definitely worth it. It also begs a simple question: are the Patriots being too limiting in their talent pool by only bringing in players who can grasp the complex option-route system? The answer to me is simple: no. The Patriots have proven that their system works time and time again, even if it limits the available talent pool to an extent. Nonetheless, whenever a physically talented receiver such as Chad Ochocinco can't grasp the system, naturally there will be fans who question it.
My only concern when it comes to the Patriots' system is whether or not it can support young players. The Patriots haven't properly groomed a young receiver since the Deion Branch - David Givens draft of 2002. Since then, the Patriots have seen all of their top receiver picks bust - Bethel Johnson (2nd round, 2003), Chad Jackson (2nd round, 2003), Brandon Tate (3rd round, 2009), and Taylor Price (3rd round, 2010).