not many soccer stadiums have parking
And this is also misleading Beckham BS.
The Orlando City stadium has a ton of PUBLIC parking and other private parking alternatives nearby. The stadium is a couple of blocks from the Arena, as well as a dozen municipal parking lots. In addition, the Magic will be building a mixed use entertainment/dining facility which will also have parking. Also, lots of smaller streets are closed down around game times, though nothing as significant as 12th or 8th Avenues.
There's nowhere near the same number of parking spots within a comparable radius when you analyze the Miami MLS site. Even if you parked everyone at the Orange Bowl (go ahead, call it a baseball stadium, if you must), it would still involve a significant trek across the Miami River, which is not exactly a great route for 25,000 pedestrians to travel while the normal traffic whizzes by.
I just don't understand the Miami site plan, without building at least ONE of the garages that the Marlins have.