As another poster said, you are comparing beer to champagne. Granted when you compare Stack, Daniels and Van Horn to Duncan and Manu, the Mavs have missed games. But you need to get a grip on reality if you are really making a case that the Mavs have been slowed more by injury.
Of The Mavs big three Dirk has missed 0, Terry 2 and Howard 8 games, and have had no lingering injuries the entire season. Otherwise, most all the Mavs injuries have been to second tier and bench support.
For the Spurs, it has been THE TWO most valuable players in last years entire NBA Playoffs, Manu and Tim who have been most hampered. Manu has missed 13 games, plus left a game with an injury early and came off the bench and/or played limited minutes to work himself back into shape 14 more games. If you can count, that is 28 games where the Spurs did not have the benifit the Manu who tore up the playoffs. And Duncan has had a very nagging PF injury effecting his mobility for over 35 games.