Bernie typically draws yuuuge crowds. So if his crowd was down, and it was across the street from Trump’s crowd, then I wouldn’t be alarmed by a “small” crowd at Trump’s event. It sounds more like it was a local thing than a candidate thing (e.g., the basketball games he referred to).
Trump had two event in Milwaukee , one with Hannity and was rally.
I think 2 events in same city with game. Trump had good die hard crowd.