I can see how this might be the case when a defense gets strong penetration into the backfield and an agile back can make a move to avoid the first defender and get positive yardage. However, what about the more frequent situation where the RB gets to the line untouched but the hole just isn't there? I would think a back like Gerhart will be more adept at creating yardage because he has the power and speed to run through defenders or over his own linemen at the point of attack and create 3-5 yards in a situation where a shiftier/speedier runner gets 1-2 yards nine times out of ten and maybe makes a great reversal of field once for a 10-15 yard gain.
I think you nailed it in the bolded portion. I have seen Toby play many times in his career, including 3 or 4 games in person. He's a good back. Much more nimble and shifty behind the line of scrimmage than he's given credit for. At the same time, the Sun Bowl against Oklahoma demonstrated that he can be bottled up by an athletic defense determined to stop him. He had one or two good runs in that game, but was mostly held in check and rendered ineffective. I think quickness trumps power when there's no hole. A guy like Jahvid Best can create big plays out of thin air, but Toby relies on a good line to open that initial lane. If it's not there, he's not going to make anyone miss. Moreover, you can't split him out wide like you can with Spiller and Best. They're more versatile. Toby's value is more narrow.
Regarding the supporting cast, Andrew Luck is considered by some to be the best NFL QB prospect in all of college football. Chris Owusu is an NFL prospect as a KR/WR. Ryan Whalen is a good possession WR. Jim Dray is a good blocking TE who could play on Sundays. Every starting OL for Stanford earned some form of All-Conference honors. OG David DeCastro is considered a high end NFL prospect. Toby's supporting cast was actually very good. That's one of the secrets that the national media isn't aware of when they predict a dropoff for Stanford's offense next season. There won't be one. They're loaded and almost all of the talent is returning.
I would say Stanford has more offensive talent than teams like Cal, Clemson, and Fresno State. Part of the reason why Toby was successful is because teams had to respect Luck. When that threat was absent in the Sun Bowl, Toby struggled.