Yeah the Pats had a rough off season.
Trust me when I say that Chad Jackson and Reche Caldwell are no replacement for David Givens, at least not yet. Depending on how much responsibility they give him, I doubt he's in for a very effective season. Not yet, anyway.
As a rookie, I think Chad Jackson can safely replace Tim Dwight. But, Troy Brown gets yet another year older (and remember Tony Martin? yeah, old receivers can basically fall off a cliff very suddenly sometimes), and Reche Caldwell as a replacement for David Givens is just mean spirited.
Laurence Maroney added to the runners group should help a lot.
Willie McGinest, they basically had already lost him...he wasn't the same in 2005 as he was in 2004. But it should be noted that the Pats didn't achieve in 2005 what they did in 2004, either.
Rodney Harrison may NEVER come back...and almost certainly will never be the same.
They have troublesome depth at LB & DL, forcing them to possibly shift to the 4-3...but honestly they're damned if they do and damned if they don't. They should switch to the 4-3 just because Jarvis Green is a better DE than Monty Beisel is an OLB...but outside of that they don't have any quality depth sitting behind their 4 man DL, or their 4 man LB unit.