The difference people were seeing wasn't so much the plays that were being called... but the players available to run them.
The Zone Run was a huge part of what Mazzone was calling. The difference was that Tyler Phommachanh was a real threat to run that had to be respected. When your QB isn't a running threat, the zone read doesn't challenge the defense, they barely respect the QB and crash down shutting down the RB. If you watch when Steven Krajewski runs the zone read he's looking for the opportunity to hand it off, Tyler Phommachanh was reading and looking for that opportunity to pull and make a play himself. When the end being read had to guess who to attack the play was open... now, not so much. You'll also notice that many of Steven Krajewski's runs are the times he surprised the defense and actually made the clear read to pull and ran for yardage on a zone run... the problem is he can't pull on some of those borderline reads because his speed doesn't necessarily put him in the best position to beat the read end one on one.
Mazzone's offense was predicated on getting the ball to athletes in space. Tyler Phommachanh was one of those athletes, possibly the best of them. The other part was the bubble screen game trying to find guys out into space on the edge.. that isn't something that has worked well for UConn, particularly the last few weeks. Steven Krajewski isn't the same type of QB as Tyler Phommachanh and running that offense is going to be tough. They can't run traditionally because the line isn't blocking it, and they can't use zone reads to setup play-action shots (which is where Steven Krajewski has had success). Add to that a missing LT who was anticipated to be an NFL prospect the last two weeks and a missing center that meant the backup who started the year off as one of the worst performers is back in (seriously have you ever seen so many times the center clearly forgot the snap count).
If it were up to me and if we have the bodies to install it and a line to protect it, if Steven Krajewski is the QB, I'd try to turn into a three-step drop quick passing game offense to open things up. You can run your slants and crossing routes which are SKs best passing plays. The challenge is that, that will expose this offense to more risk and Steven Krajewski has been turnover prone. If you can start to threaten the defense with the passing game (or make them think that you are trying to threaten them), then hopefully you can start to get more balance with the run, allowing you to take shots on play-action.
