"I'm very, very happy with where Aldon is right now," McCarthy said ... before adding, "Aldon is off to a very good start. He's impressive. Still very impressive."
It's a pretty shocking report from the Cowboys head man ... Aldon hasn't played a down in the NFL since the 2015 season -- and has battled legal troubles and substance abuse issues during his time away.
But, Smith's sober now, and he told us this offseason he busted his ass in Jay Glazer's gym in L.A. to get his body back into NFL shape ... and clearly, it's all paying off.
"You can see his power and his length is extraordinary," McCarthy said.