I think the season might be over. My wife and I went, we got out tickets online at Ticketek.com.ar. It was a lot of fun, but what we didn't know was the ticket actually gets you in for two matches, one in the afternoon and one later in the day.
Even without matches Bocha is open and you can have food and hang out there, which is also really nice. Across the street is the casino and horse racing track which can be fun too. They have a lot of little food events on that side with pop-ups.
Lollapalooza is in the polo club this year I think, too.