The Cowboys' best pass rushers need to be rushing the passer, not dropping into coverage: In the 3-4 system, as we all know, the primary pass rushers are the two outside linebackers. This is problematic, however, as opposing offensive coordinators can find ways to scheme players like DeMarcus Ware and Anthony Spencer into coverage - usually by placing multiple receiving threats on one side of the formation.
In 2012, Ware played 896 snaps against passes and was asked to drop into coverage 64 times (seven percent of the time). Spencer went into coverage almost 20 percent of the time (172 out of 872 passing plays). 4-3 defensive ends, on the other hand, almost never drop into coverage (Ware was in coverage once all season from a 4-3 DE position). In other words, in a passing league in which defensive priority one must be to put pressure on a quarterback, a scheme in which the players who are most likely to do that can't be in position to do so is, frankly, suicide.
http://www.bloggingtheboys.com/2013/...-wasnt-working