[NOTE: This post is intended as a supplement to 'Assessing Ariza.']
Why is the ability to ‘create’ off the dribble so important?
The answer should be fairly obvious after last season when the Houston Rockets routinely failed to score late in the 4th quarter of close games. The NBA is distinct from college basketball in that set offenses do not function well against tight defenses late in close games.
This is why teams routinely put the ball in the hands of a guard who can break down the defense off the dribble and either create shots for himself or his teammates.
These players are usually the team’s ‘go-to’ players.
Ray Allen is the only guard who comes to mind who doesn’t attack off the dribble but is considered a ‘go-to’ option. Even then, he does have the ability to create for himself off the dribble.
-ESPN Houston Rockets Affiliate- Rahat Huq - founder, editor email: 
[...] McGrady issue is momentous because a priori to our assessment was the knowledge that nearly every championship team in this league’s history has featured a perimeter player who [...]
[...] Trevor Ariza will never become a primary ‘go-to’ option for a good team. This is simply … and most likely will never develop this ability. He is a ’slasher’, not a ‘creator’. [...]