I agree with you that it all can't be blamed on the situation last year, but I'd put a heavy percentage on it. Not sure Will Smith is a good comparison, as he was a rookie in 2004 and had significantly increased playing time in 2005 over 2004.
How about Darren Howard ... only played limited time in 12 of 16 games and registered 4 sacks. Not his normal production but still on pace for about 5-7 sacks in a full season.