Tolbert's preseason touchdowns are a result of a) timing and b) preservation of a rookie back who is getting ready to handle 300 touches this season. The last thing he needs is to get hurt during a meaningless preseason goalline carry. Tolbert should see some spelling time but Matthews is a strong, powerful back as witnessed by him knocking Urlacher on his arse a few weeks ago.
Additionally, LT and sproles were not a strong rushing combo last season. You have slow, injured LT and 180 lb sproles totin the rock behind a somewhat dinged line. PLUS (oh, don't get me started) PREDICTABILITY. Hopefully, they can develop some imagination this season and that rushing rank will improve, especially with some fresh rookie legs.
"Gunga la gunga...which means on your deathbed you will receive full consciousness, so I got that going for me." Bill