Through the first four games of the 2010 season, rookie second-round defensive end Jerel Worthy had five tackles and one sack, while fellow rookie end Mike Daniels had one tackle and one sack. Neither has become a regular in the starting rotation, although Worthy has seen a lot of time at end in the base 3-4 defense. With the ends, the Packers were giving up 4.4 yards per carry through Week 4, less than what they allowed last year (4.7).
It is entirely possible that Worthy or Daniels will have long, successful careers at the DE spot, but recent history suggests that neither of them will light the world on fire this season. Consider: in his first season, Tampa Bay DT Gerald McCoy managed 28 tackles and three sacks. Kyle Williams of Buffalo: 53 tackles but no sacks. Arizona Cardinal Darnell Dockett, one of the premier 3-4 ends in the league, had just 3.5 his rookie year. Evander "Ziggy" Hood of the Steelers had just one as a rotational player. Production is hard to come by as a rookie DT, even when the player stays healthy.
Injuries are also quite common with highly drafted DT/DEs in their first years. Packers fans will remember B.J. Raji as either hurt or ineffective with an ankle injury in 2009, and scarcely need to be reminded of the ignominous career of Justin Harrell or the troubles of Mike Neal. Nick Fairley, Jared Odrick, Peria Jerry, Brian Price, Linval Joseph and Dan Williams, highly drafted DTs all, also had injury problems in their respective rookie years. Rookies at all positions struggle with the adjustment to the NFL, but defensive tackles have it harder than most.
The thing about DT/DEs is that they tend to be gigantic, immensely powerful men. In college, they can just overpower smaller, weaker offensive guards and centers that are never going to play in the NFL, but everybody in the NFL is huge, strong and quick on their feet and won't let you just bull-rush them to death. It takes a while for rookie DTs to adjust to not just crashing through people anymore. Ndamukong Suh did not have that adjustment period because he is huge and strong enough to overpower college AND NFL linemen, but Suh is a once-in-a-decade prospect.
Bob McGinn mentioned in his Wednesday chat that Worthy had little trouble beating college guards into the backfield, but NFL guards generally don't let you get away with that. It'll take time for him and Worthy to develop NFL-caliber pass-rush moves, and even with Mike Trgovac coaching the defensive line these days, don't expect it to happen overnight. They should be most effective as part of a rotation with Raji, Neal and C.J. Wilson, but a consistent pass-rush from the D-line--with the exception of the Chicago game--has yet to materialize. The Packers can only hope that some of their highly drafted DTs figure it out eventually. Clay Matthews can only do so much.