We'll have to wait and see what comes out but I don't think this is a bad sign. In war you lose equipment and aircraft. It's silly to think the US wouldn't lose some during the course of the war. After all, the OP to this thread highlighted all of the advantages Iran has. Yet we've wiped out quite a bit of their military infrastructure and have complete control over the skies. Russia can't say the same though for their little adventure ;)