Well, if you're only looking at ratings for the past few months, and only in a few other markets, you're not going to see long term trends, right?

Your question about what's different about Chicago radio is a fair one -- is it different market demographics? Is it that B96 is a mess and that many don't want to listen to the commercial marathons on Kiss when they can fire up Spotify instead? A combination of all of the above?

Some of the more successful CHR stations I've sampled outside of Chicago (looking at you, WIXX, Green Bay) just sound so much better than B96 or Kiss. More listener engagement / call-ins, more local interest stuff / community connection, shorter commercial breaks, and less repetition.

Speaking of, Sean Ross had a great article last fall on repetition's impact on CHR ratings. I have to admit, I haven't checked out B96 or Kiss in a while, so not sure where they fall on the spectrum of how heavy they're hitting the hits, but Sean's article is here:
https://powergold.com/what-is-the-sweet-spot-for-chr-power-rotation/

These discuss the longer term trends for CHR:
Edison Reseach: CHR shares fell 32% during last 4 years
https://www.edisonresearch.com/chr-contracting-hit-radio/

Inside Radio: News/Talk surges to record high, CHR shrinks in full year 2020 ratings
http://www.insideradio.com/free/news-talk-surges-to-record-high-chr-shrinks-in-full-year-2020-ratings/article_cb62b406-6d0d-11eb-806b-93e86cbc474b.html