Resident. Once inside the park, there are numerous stands with local beers. Was there last week, about $16 a pour.
I'm a fan of HalfDoor. East Village is along the path if you took the trolley into the area. (Have not been yet). Lost Abbey is a couple blocks away as well (Have not been to this location yet).
Big fan of Half Door Brewing. Get there early enough, and you can pregame on the top deck, while staring at Petco. Not sure if Stone is still next to Petco, but, I can't see if being worth it unless they have some vintage stuff on. Lolita's at the Park is always fantastic for food, especially in a pinch. They usually have a few local taps on as well.
Barley Mash is close and has decent taps. Social Tap was solid last time I was there and is connected to Gallagher Square. Agreed on Half Door as well
Stone is gone. I recommend Lost Abbey myself. Pretty nice taplist and only about 3-4 blocks away. Resident isn't too far either. Thorn Brewing is about a 10-ish minute walk, Mission Brewing is 5 mins away as well.
Ohhhh this thread has come just in time since I'm catching a game at Petco later this month, and the Pacific Surfliner is opening back up (again).