Green Bay had three non-Fox 'big switch" affil switches in the 80s-90s.
First, WLUK (then ABC) and WFRV-WJMN (then NBC) switched in 81. This was during the period when ABC was using its strength to get better outlets (it was usually No. 3 in two-VHF-station markets) and saw a chance to improve itself by getting the WFRV-WJMN combo. (It was good for Green Bay viewers as well, as WFRV had never carried David Letterman, but WLUK did).
The second came in 1991, when WXGZ (now WACY), which had been the Fox affil, shut down because of bankruptcy, and Fox moved over to WGBA.
The third came in 1992, when CBS bought WFRV-WJMN as part of a package deal including WCCO-Minneapolis. Reports were at the time that CBS (at the time on WBAY) wanted to sell WFRV-WJMN, but didn't. Instead, it moved the affiliation to WFRV, with ABC heading to WBAY.
There was a fourth, by the way - WPXG, a Paxson-owned station, was bought by Acme Communications in 1999 and became WIWB, a WB affil (it carried Pax programming in off hours for a couple of years but has since dropped it and Green Bay has no affil with the Pax/i/Ion/whatever it will be called next week network). With the WB/UPN merger, Acme switched its stations to the CW, and WACY, a charter UPN affil after it got out of bankruptcy, ended up with MyNet.