I'm with those who think that bringing in increased athleticism off the bench will make us more competitive. Further, the bench will not only come in as a unit but will be called upon to provide an answer or change of pace in the face of a difficult match-up. If Ray Ray is getting killed by a super athletic, attacking, or tireless two, TA, Miles, and hopefully Giddens will be there to spell him. Likewise, Darius and Walker may give us flexibility off the bench against big threes and perhaps even some weaker 4s or even 5s (think Dirk, Camby, Aldridge, or Okur). In summary, we have two guys off the bench that can create mismatches and shots for themselves and others, TA and Miles (allowing that they are questionable), a great pure shooter, House, a steady old hand, Cassell, a hard-nosed low post 4, Powe, and a potentially productive shot-blocking and rebounding 5 who is a true 7 footer, O'Bryant. That isn't bad for an achilles heel.
Just a word on Posey: economically, Danny did the right thing. He won't be worth the MLE for 4 years. By the end of the season, it became apparent that his best role was a smallish 4 who could spread the floor. While he may be able to do that for a few more years, if that's all he can do, he's not worth playing over Leon in two years, forget paying him 6 million. While the ability to defend LBJ may not be the best barometer of continued defensive prowess, the fact remains that James' eyes lit up every time he saw Pose during that series. He went to the basket without fail and scored, was fouled, or found the open man constantly. Pose was brought in to match up with guys like that and give Pierce a rest, but given his performance in the playoffs, age, and Pierce's success in filling the defensive stopper role, there's little reason to keep Pose around for more than another year or two.