At the height of Austin's game, which didn't last long? I probably agree with him. Austin had an incredible burst in and out of his cuts, especially for his size. His hands weren't as good as Dez's, but his ability to gain separation was better. Dez is a different-type receiver who has shown he can excel and be one of the best in the league when Romo was throwing him the ball. I don't think that is coincidental.
You've been very short-sighted on this one IMO, x. When a receiver goes from playing like one of the best to being targeted too much for the production we're getting, either A) his legs have fallen off (which I don't believe is the case), B) the system has changed (which it really hasn't other than the fact we've been running the ball more since 2014, which happened to be one of Dez's best seasons) or C) there's something not working between the QB and receiver. Romo pointed out that the problem is C, which means it's primarily on Dak's shoulders.
Again, that doesn't mean I think Dak is doing poorly at QB. There's just a type of throw that he's not making that Dez excels at catching. Every receiver has his strong suits, their wheelhouses, and Dak just isn't pitching to Dez's.
The good news is that if they can get on that page, this offense becomes even tougher to stop.