You can argue too that I don't think iHeart really had their full heart set into the sports talk format since they never changed the call letters from WRNW to something more specific like KGMZ did in San Francisco, and it just never really had listener buy-in thanks to layoffs taking out good hosts before they could establish themselves. The format just had the feel of something they'd try for a few months and if it worked, good for them because they wanted to do something around the Badgers rights, and they just happened to luck into the Packers rights on top of that.
Even GKB had been shifting around for years with 1510, 540 and 1290 over the years until Scripps finally put the for-sale sign out for the Radio City stations. The format in Milwaukee just has never felt like it had a solid home at all unlike Madison and Green Bay, where WTSO and WDUZ/WNFL found their sports niche decades ago. WTMJ probably should have shifted to all-sports around the time Brian Manthey was holding forth on Sports Central a la WIP's transition, but Sykes, Wagner and Green doing fine made that a non-starter.