It is interesting to me how Schwartz was able to take Pettine's guys and improve the D...especially the run D...Then Rex takes the same guys (basically), installs a similar system to Pettine's, and once again is getting mixed results...Maybe the schemes are too confusing for the players...Maybe they do leave no margin for error...But I certainly think there is a chance that complex or not, after all these years of seeing it, teams know how to attack Rex/Pettine's Defenses with more precision...Especially teams with good QB's...So I think it's a combination of things...