I've taken the Wolverine a few times, typically from Detroit to Chicago. The stop in Detroit is in a fine part of town, not far from the DIA and other cool things, but the station area is not a hopping place at night. It'll likely be pretty empty, YMMV on how you feel about that. I figure you will be with other fans who make the same transportation choice, so that's probably good for feeling safe in a city you don't know. If you hang out in the station till your ride appears, you'll be fine. I'd do uber instead of parking a rental there, personally.
The A2 stop is close enough to the stadium, and if you are exploring the campus it's sort of on the way to the stadium. Depends on how much you like to walk. You will get to avoid the hassle of game day parking and the traffic headed into A2. There is a lot to do there after the game, so I wouldn't worry about filling time till your return train.
The train itself was always fine. Clean, charging ports, etc. I found it to be reasonably on time as long as the weather isn't crazy.