Do you know what makes someone a starter in the NBA?
Calderon starts, therefore he is a starter.
Does he deserve to be a starter? Yes, absolutely. If you were to list the top 30 point gaurds in the NBA, he is on the list. No question. I prefer him over lots of guys. Are there any backups that are better than him? I doubt it. (Don't say Jarrent Jack).
Now, he's pretty average as a starter, but he's still a starter.