No, it was the crest, but an older version of the crest, similar to the version that was in use when I graduated:
The emblem originates from the athletics end of campus since it is a flourish on both ends of the UW Field House. It was actually a graphic designer hired by the medical school in the mid '80s who first turned the Field House "W" into a crest that would be used as a logo by an academic department.
https://news.wisc.edu/who-knew-19/
The two-dimensional version of the crest was soon adopted by the rest of campus and later refined. There used to be a complex version and a simplified version, but the complex version (seen on that flag in my previous post and in Madison Cone's tweet) is largely being phased out.
https://daniellelawry.com/portfolio_page/university-of-wisconsin-madison-rebrand/
Here is a newer flag with the latest updates to the crest and university wordmark: