Good call on Vincent Jackson. Wayne is certainly a bit old and would represent a "more of the same" mentality. Jackson is an absolute playmaker and would add an offensive element that is sorely lacking.
However, on defense if Belichick wants to continue to emphasize having smart players who really understand stategic concepts it would make sense to target veterans. Plus, there is a certain level of physicality needed to play in the NFL that this staff doesn't seem to understand how to implement. This BAL/PIT game makes that painfully obvious.
This fix isn't a simple matter of adding raw talent. "Old guys" like Reed and Freeney probably have 3 or 4 years of playing at a very high level and would represent a quick, sure-fire fix, IMO.