I know Detroit was in the running, but it seems like their bid was far less serious. It was a couple of MSU alums and current NBA owners (Dan Gilbert - Cavs & Tom Gores - Pistons) leading the bid, so it seems like they could have been a lot more serious about it if they wanted to. They scrapped plans for a new outdoor stadium, and were going to play in Ford Field, which hurt them. There was also a strong push AGAINST the bid by fans of Detroit FC, which has actually grown to be a substantial fan base for a low tier soccer club, so I think MLS was worried about granting a team to a city where the hardcore soccer fan base was opposed to the team.