I think WHO you defeated, or lost to, is very relevant. A team can be 10-0 having played "no one" and in my mind, they are at best unproven (Army). "We" are asked to draw conclusions based on incomplete evidence. I think also items like recruiting comes into play. Otherwise, we just "NFL" the numbers and count only wins and losses as all the same, so Army should be co-number one. We don't, I don't anyway.
Now, maybe Indiana is the real deal, we'll find out soon enough. Maybe Army is as well. We get more information as the season progresses. We never have ALL the information. But most folks don't think wins and losses are all the same.