Gregory's pressure rate is much higher than Taco's.
Just thought it was interesting considering how you described them.
Gregory gets a lot of pressure but just doesn't end up with a lot of sacks. Marinelli is obsessed with running stunts which end up limiting the DEs opportunities to get sacks. A college coach that I know refers to the two players running a stunt as the crash man and the loop man. On an End-Tackle stunt, the End "crashes" inside into the blockers and the DT loops around to the outside (A Tackle-End stunt is the opposite with the DT as the crash man and the DE as the loop man).
For some reason, Marinelli seems to use a lot of End-Tackle stunts on the Right side but more Tackle-End stunts on the left side. That gives DLaw as the loop man more chances for sacks but gives Taco/Gregory less opportunities as the crash man.
Stunts are Marinelli's way of mixing up pressure without blitzing. Some offenses take advantage by running against the Cowboys stunts. If the offense can guess which stunt the defense is going to run, they can take advantage with specific run plays that exploit that stunt.