I moved to Los Angeles in 2004. The next year I organized a softball team, mostly coworkers at the time. There are six of us that have been playing since we started, going on seven years now, even though we've almost all since changed jobs. Even though it's "just softball" (and our league is about as uncompetitive as possible without being totally beer-league), we've all made attempts to make it to games that bordered on absurd. I'm talking like, having a game end like 90 minutes before a flight I had booked, so I brought my luggage to the game, planned for a cab to arrive right as our game ended, and changed in the back seat of the cab on the way to the airport. Sure, I could have just skipped the game. I don't know if it's as contrived as "not wanting to let the team down." But these guys were my friends and I wanted to be there. Outside the six of us, we've had countless guys come in for a season or two, and then kind of fall off and stop playing. Almost all my post-college "good friends" -- the kinds of guys I invited to my wedding, for example -- have played on this softball team.
So I've thought about this a lot. I guess I've concluded that male friendships in particular are more easily forged in some environment of "commitment." In the "you've been there for me, so you're a good guy, so I can feel comfortable about opening up to you about subjects you only bring up with your good friends," sense. Also, I don't think this happens overnight, at least not for me. We were playing for two years before we'd do something like get dinner after the game. It was another long while before we'd talk about deeper friendship stuff like career advice, girlfriend problems, etc.
Hopefully I'm not making this sound like you can only make friends when you're a "bro" who plays sports. When we're younger, these organizations exist everywhere: high school, college, school clubs, sports teams, whatever. Just any place where you're expected to give more than what may be convenient and everyone else does the same. Going back to the softball team, let's say I get two emails the day of a game. One guy says, "hey my boss wants to pull me in a meeting that probably run long, I managed to tell him I have a hard stop at 7:00pm, but I may be like 10 minutes late to the game." Another guy says, "hey, I had a big lunch, I'm gonna skip the game." Which guy am I going to end up being friends with?
So I suppose my conclusion, at least for me personally, is that it's usually not enough to find people I have something in common with, but something in common that we're both committed to. It's tougher to find that after high school and college, but it's not impossible.