On my second trip to Oxnard back in '06, I was standing by the far fence one day watching the defensive linemen drill. A visiting coach turned to another, pointed at 2nd year starter Chris Canty and said, "that's what a five-technique looks like."
Canty defined the prototype. He is 6'7" and weighed 295 lbs. at the time. He's "high cut," with long legs and long arms. He had the length and the power the team looks for. A source told me the prototype Dallas end goes 6'5" or so and 285-295 lbs. starting out.
The Cowboys want linemen who can two-gap, taking on offensive tackles head up and maintaining the line of scrimmage if they are double teamed. Wade Phillips runs a more one-gap scheme, but he and Parcells want linemen who can get off blocks and chase down plays run away from them. Jay Ratliff's pursuit skills are a big reason why he was moved inside and why he gives centers such a hard time. His punchout gives big guards a hard time (I've seen him bend 366 lb. Leonard Davis backwards with a two-hand pop to the numbers.) Smaller centers have that much more trouble containing him.
The difference between the good and the exceptional five technique is the ability to contribute on 3rd downs. The average guys leave the field for situational rushers. The big timers, the Richard Seymours, generate a rush pushing inside or coming around the end on first, second and especially third down.
Canty's inability to produce on third down is one reason why he plays for the GIants now. That lack of late rush is why fellow '05 draftee Marcus Spears only received a 2nd-round tender this year (more on that in a minute). It's why the Cowboys were looking at ends in the early rounds last year and why DEs like Jared Odrick and Tyson Alualu rank high on their board this year.
Dallas has three dominant rushers in Demarcus Ware, Ratliff and Anthony Spencer. If the Cowboys can find that three-down end, in the Elvin Bethea mold, they'll have another interior terror to pair with Ratliff. Wade Phillips will be able to put QBs on the run with only four rushers.
This isn't a need spot, but if an end sits atop Dallas' board in any of the early rounds, he may well get a call from Jerry Jones. You can never have enough rushers.
Note: Spears signed his tender today. The early reaction has him penciled in at left end. As I see it, Spears also became trade-eligible the minute he signed that contract. Dallas has four DEs in Igor Olshansky, Spears, Jason Hatcher and Stephen Bowen. 3-4 teams only carry four and the addition of an Odrick or the like would mean Dallas is overstocked.