I like your roster construction a lot, Who, although I see it more as a "team of the future" team that can be competitive now (which I think is what you suggested).
You answered the big question about Kevin Martin. The other big question is Martin's health: he's only been completely healthy in one out of six seasons, and has missed 25+ games in each of the last three years. Is this a luck thing, or is it a legitimate concern?
Also, what type of stat line would you expect out of Splitter and Randolph this season?
(1) Yep, I see this as team for the future ... one that should become a contender in another year or two depending on how quickly the young big men grow (Randolph, Thabeet -- need them to be impact defenders + need Randolph's shot-creation to round out the offense).
In the meantime, I expect this team to be a very good regular season squad but one that isn't built for playoff success.
(2) Kevin Martin's health -- legitimate concern -- he seems a frail.
(3) I would peg Splitter in the 28-31 minute category. I think he is good for 14-15ppg on a TS% of 58-62%. Maybe 7 to 7.5 rebounds and 2.5 assists. With good defensive play.
I am thinking 30-32 minutes a night out of Randolph (but I would love to keep him out there for 34-35 minutes) and would expect him to score 14-15ppg (in 30-32) but do so with less efficiency (54-55%) while also adding 8.5 to 9 rebounds a night. The expectation for his defense is for it to start off as poor but gradually improve throughout the year and become an average defensive player by year's end. Also adding a combined 3 to 3.5 blocks/steals.
Edit: Chris Paul's + Kevin Martin's efficiency should allow both players to get enough shot attempts off in around 30 minutes to score 14-15ppg.