HomeSec is not saying that Alexander is a flash in the pan, but that his O-line is not what it was and he's not as valuable right now. OTOH, Thomas didn't have a great game, but he did get a TD in the second half, and caught some passes for good yardage. Alexander had slightly less overall yardage and caught a TD pass.
Let's not forget that neither of them have played a full season yet. They both won their jobs due to injury of their incumbents.
IMNSHO, they are about equal right now, with Thomas having a slight advantage. In any case, expect both backs to have good games this weekend.
With that in mind, the QBs become the focal point of the trade.
Getting Garcia for Bledsoe is a steal. The thread originator definitely got the better end of the deal.