actually it much more complicated, as ronaldinho have a contract with nike, so any actual money from shirts sales goes to nike, while Milan is sponsered by adidas
Those are his image rights. Milan are trying to earn from Ronaldinho by :
1. Mediaset (owned by Berlusconi) is paying €61.7 million a year only for highlights rights and as broadcasters they pay almost a billion for live coverage of Juve's, Inter's, Roma's home matches etc. Then they're sellling these rights.
With Calciopoli and with EPL+La Liga gaining more interest from the world public Mediaset lost a lot. There wasn't much interest for serie A.
After Milan won the CL last year there was a growing interest, especially in England. Serie A was back on Brittish screens and it resulted with millions of € for Berlusconi.
Now the question is how to keep the attention of the world public and even make it grow ? Of course, by winning in Europe and buying world star players.
Everyone would like to watch Ronaldinho and everyone will buy the TV rights from Mediaset.
2. Winning more sponsors.
3. Selling more tickets.