To me, the essence of the OP's question pertains to the wisdom of making decisions based on a small sample size.
I think it's a valid question.
We COULD look at his back shoulder TD throw to Benjamin, recognize that we never saw Tyrod make that throw, and extrapolate that to say Peterman may be the best bad weather QB ever.
That would be a ridiculous extrapolation. But so too might be tossing him over one half of bad football.