The problem with all this "replacement" talk is that either the player has to want to come here (i.e. we have the most cap space free that we are willing to offer) or the team has to want to trade our targeted player (in which case we would have to have something to offer in return). So it's really hard to target a future replacement with any realistic accuracy, unless we are just musing our fantasy desires...which is also fun, of course.
So yes, Kevin Martin would be an awesome Ray replacement, but he's under contract for a while, so how do we get him? Same with Anthony Randolph for the "KG replacement thread." How? Randolph will be a restricted FA. So his team will have the right to match. So by that point he will either be worth big money, and his team will match, or he will not be worth big money, so the C's will have to overpay to take him away...and that never really works out well.
So it's really hard to target a realistic replacement for "Celtics Player X" without being able to predict future drafts, the next CBA, player disgruntlement, other teams' desires to rebuild, etc.
But, Dwight Howerd (FA 2012), Antony Randolph, and Keving Martin would be great replacements for Perk, KG, and Ray
Rondo/Kevin Martin/Pierce/AR/Dwight in 2012-2013 baby!