First of all, this isn't a David West thread.
And West is 35 years old. West isn't going to be asked to do too much and I don't think anyone expects him to come out and give the Spurs 30 minutes a night of 12 and 8 like he did in Indiana. He'll be the 4th big off the bench. Tim/LMA will see over 33-35 mpg each when it matters in May/June.
And West has always been an efficient, team oriented player, who can pass, shoot and make smart decisions. He's been known to have one of the best mid-range jumpers in the game for the past 9 seasons for big men. Not to mention he shot 50% from 15-23 feet out last year according to bball reference. It doesn't take a rocket science to see how his efficiency and floor spacing can have a positive effect on the Spurs' overall efficiency in the limited minutes he will recieve.
Josh Smith, while talented, has been anything but an efficient and effective team oriented player. There's a reason why Hawks let him go, there's a reason why Pistons cut him. I'm not saying the move is terrible, it's probably the best the Clips could do to improve their front court from a strict talent perspective. It's a fact that he's been an inefficient, dumb player at times and that's something that's fair to critique.
You can read this again to get a better understanding of my reasons: