Other more advanced metrics (S&P for example) they adjust for the quality of the opponent. The weakness without a couple more games is that the adjustments may not be quite what they should be. So waiting is fair.
But right now these advanced metrics show a defense somewhere in the 3(!) to 12 range, adjusting for opponent strength so much as they can.
I think you are also overlooking the fact that SMU’s primary QB, Preston Stone (who came out because we put so much pressure on him he was totally ineffective) is a 161 PER passer. The idea that we haven’t faced a guy like that isn’t true. It’s just that we so completely dominated with pressures that he was subbed out. There may be some guys who are really excellent passers whom we couldn’t pressure like that—Cam Rising comes to mind—but there aren’t very many in the whole country who are that kind of passer and whom we couldn’t pressure into making big mistakes.
We won’t see more than maybe 1-2 in our league.