Dean Oliver can.
Oliver, production analytics director for ESPN Stats & Information, pointed to one play I missed when explaining why Jackson's performance against the Bills beat out all but six others by Kevin Kolb, Matt Hasselbeck, Sam Bradford and Alex Smith last season.
QBR recognized Jackson's end-zone pass for Bernard Berrian as significant for drawing a pass-interference penalty. The penalty turned third-and-2 from the 6-yard line into first-and-goal from the 1. Adrian Peterson scored the go-ahead rushing touchdown two plays later.
Jackson led the Vikings to a touchdown on their next possession by passing or running for all three first downs on the drive, including one in the red zone. Jackson then threw a touchdown pass to Sidney Rice on the Vikings' next possession, blowing open the game, 28-7.
The two interceptions Jackson subsequently threw didn't matter so much, although they dragged down his conventional passer rating to 85.0 on 158.3-scale.
I've reproduced the chart from the previous item. It shows the 10 highest single-game QBR scores from 2010 for the quarterbacks in question (minimum 20 action plays per game).
Jackson's mobility accounted for some of his appeal from Seattle's perspective. QBR takes into account quarterback rushes, among many other factors. If it invites closer examination of quarterbacks' performances beyond the obvious, all the better.