I find this line of thinking ridiculous. As with any complex problem--there is no single answer, but a combination of several to many factors that are the cause.

The offensive explosion is a result of many changes:

Massively improved coaching, play design, and play calling
Improved play from the offensive line
Improved play from the QB
Improved play from the WRs and TEs--are we dropping the ball? are people where they are supposed to be?

All of the above, and probably more factors, have led to the offense's success. And I believe Gurley is a top three back in this league, but to single any one member for the key is ridiculous.