Dallas does not run a WCO; not since Coslet was OC. Parcells' offense is its own animal altogether. A little background:
The WCO is built off of a very athletic and super-accurate QB who can run designed sprints to one side or the other and throw on the run. Nobody did it better than Joe Montana, Steve Young, John Elway, and Brett Favre. Throws are short and so to compensate for their short distance the QB must lead the receiver to gain YAC. Big WR's are staples of this offense because of the crossing patterns and the need for accuracy. Jerry Rice, Cric Carter, and Terrell Owens are perfect WCO WR's. The WCO uses the TE, RB, and FB as receivers. You don't power-run from this offense, so plays must be designed to create space in order to run the ball-- runs are almost all draws and wide toss plays-- in this offense a short pass is considered a run. RB's are slightly less physical but better athletes-- almost built like WR's. Ricky Watters, James Brooks, Robert Smith, and Ahman Green are perfect RB's for this offense. Keith Jackson, Brent Jones, Shannon Sharpe, and Rodney Holman have had success as WCO TEs.
The Gibbs-Zampese passing offense calls for motion, timing patterns, and pocket passing with a sprinkling of designed rollouts to keep blitzers honest. It requires a QB with a strong, accurate arm to throw to any spot on the field with perfect timing. A mix of WR's of any size are featured as speed and pattern running are the keys to this offense since the QB is throwing to a spot which could be 15 yards away or 30 yards away. Henry Ellard, Michael Irvin, and Wes Chandler are perfect WR's for this offense. This offense pounds the football on the ground to force the defense up and bait for play-action, so hybrid players are keys to fooling the defense-- that is you must have TEs who can block or catch (or a combo of specialized blocking TE and specialized receiving TE or "H-Back") and physical RB's who can run, block, or catch. Chuck Muncy, Emmitt Smith, and Eric Dickerson are perfect RB's in this offense while good HBack/TE combos would be Clint Didier/Donny Warren, KellenWinslow/Pete Holohan, and Jay Novacek/Alfredo Roberts. This offense can pass all day or power run from 2-TE sets, but it calls for a lot of talent to be run correctly.
Sean Peyton uses multiple formations and motion like the Gibbs-Zampese offense but doesn't call for the timing passes and such. Bills Parcells' offenses have always called for physical, smash-mouth players and have often used powerful TE's who can catch, physical, disciplined WR's who can block, and a host of RBs who can keep the chains moving in support of a featured back who can grind time off the clock and make big plays. Joe Morris, Curtis Martin, Otis Anderson, and Julius Jones are ideal featured RBs; Mark Bavaro, Howard Cross, Zeke Mowatt, and Jason Witten are perfect TE's, and Mark Ingram and Keyshawn Johnson are perfect WR's. This offense also features a "utility" type RB who catches, runs, and mostly plays smart football. Utility guys from the past have been Tony Galbreath, Dave Meggett, Keith Byars, Richie Anderson, and maybe our own Marion Barber.