In my headcanon this is the middle or third part of a trilogy. You see, after his divorce the Gava went through an accelerated midlife crisis and started drinking a little more than usual. Degenerate parties, heads hanging over toilets, crashed sports cars, and so on. Like punching one or two paparazzi and going viral (not in a good way). That sort of thing.

Either way, after some shennanigans Gava's manager convinces him to meet with a few functionaries of the national team, basically getting the band back together. This comes with a catch though, because they don't actually want him to win, it's just politics (more or less implied). So after being somewhat hesitant at first he drives through his old neighborhood and sees a bunch of happy young boys playing soccer and rediscovers his own love for football. He calls up his manager and agrees.

Gava struggles. He barely manages to get in shape, maybe using unconventional methods, and somehow him and his team of misfits end up second place during the qualification round of the upcoming World Cup in Italy. Gava gets cocky again and decides he wants Sour Puss back. He falls into bad habits, like getting in fights with fans and has his lowest moment when a kid tells him he's ashamed of having worn Gava's Jersey. He realize him and Sour Puss aren't in love anymore and all she cares about is fame.

He apologizes to the public and him and the boys take the journey to Italy. They win the World Cup against Germany and Gava makes up with the fan he assaulted once. He retires and moves back to his old neighborhood coaching a youth football team...

Something like that. I guess this is pretty much just Major League but with soccer. He could fall in love with a more humble woman along the way. Someone he overlooked. Like a cute veterinarian who treated his dog. You get it.