Dallas just had too much talent and experience. Kidd, Marion and Nowitski are perennial post season players. Guys are certainly old but their experience makes up for it. OKC will be fine. Westbrook will do nothing but get better. I remember years ago when Rajon Rondo was catching flak from the media, said he shouldn't be starting, blah blah blah. He just needed time to grow, same with Russ.
Unfortunately for the Mavs, James and Wade both have playoff experience and finals experience. The experience factor will be greatly diminished and the better team will win.