Pretty sure Bryant never got sent back to Iowa once he got called up other than maybe an injury rehab stint at some point. The stink with him was he was ready to go out of spring training his rookie year but the Cubs kept him at Iowa to start the season for like 10 days so they would get another year of team control out of him which caused a bit of a riff with Boras. Rizzo originally debuted with San Diego and had a rough go before the Cubs traded for him. He started in Iowa then was called up and never went down again after that his 1st year with the Cubs. Schwarber, Baez, and Happ all got sent down after some struggles so he is right there but he's way off comparing the situation to KB and Rizzo's. Another example of why I think Jed is in over his head sometimes as most of those guys he mentioned had more minor league run to develop than Shaw did. KB and Schwarber were fast tracked a bit but they were way more ready development wise for the moment than Shaw was.
I'm not down on Shaw but he obviously was not quite ready based on the slow start. He's only had 152 plate appearances at AAA so hopefully they can work on some adjustments and get him swinging a hot bat and call him back up when he's ready. My guess is they send a pitcher down when Brujan is ready and that buys some more time for Workman too. Guess 3B will be a platoon for now, hopefully they get Workman some regular starts there to see what they have so they don't have to rely so much on Berti and Turner to cover 3B duties too.