The change (to Mathews as their feature back) is coming sooner rather than later (not sure about this season). While Tolbert is a nice RB, Mathews can be special. The more you watch Mathews, the more you realize he's one of the most electric backs in the NFL. He runs with a lot of power, as well. That combination is devastating.
Don't think Mathews getting the start these last 2 weeks doesn't have meaning. Tolbert is covering punts, LOL. That said, you have to hand it to Tolbert. He's taken advantage of playing in that offense, but he's simply nowhere near as talented as Mathews, IMO.
Patience. You just have to realize it may not happen this year.