No you couldn't. You could argue that players have a heavier weight to carry and haven't been able to carry it. Peter Jok has not regressed (hasn't gotten much better defensively, but is playing much better offensively), Brady Ellingson has not regressed (look at his 3pt%. That's what he's here for). Nicholas Baer is our second or third best player and teams are keying in on him now. He has not regressed. Dom Uhl has always had a maddening inconsistency, so to say he's "regressed" would be a real stretch. I just don't believe he's improved much since being at Iowa. That's between the ears. Experience alone should allow for more success. It's fair to assume that Isaiah Moss is as good or better now than last year.
The only player that you could argue has regressed is Ahmad Wagner, although the sophomore slump is something we've seen a lot of at Iowa. It looks like Wagner's about to have a "Melsahn Basabe second year."
It seems silly to say that all returning players have regressed, while our best player is putting up video game-like numbers, our sharpshooter is shooting the ball at a <50% clip, and Baer is nearly doubling almost all his statistics from last year. Defense, particularly in a zone, is a group effort, and the returners don't have Adam Woodbury to be an anchor in the post, Clemmons to be a stopper, or Uthoff to block shots on the perimeter. This is a huge adjusting period.