Sports normally are a great way to spread public diplomacy, who doesn't enjoy watching international games or exhibitions and seeing some pretty amazing talent. And, it's way more interesting than watching a meeting take place and the canned political statements.
But, as with the Georgetown-China basketball game, things can go wrong. It's hard to say why the players felt like they needed to start swinging at each other (especially when they knew they were on a goodwill tour and this is highly anti-goodwill), but it definitely wasn't planned. Public diplomacy can also run into hiccups, whether it's comments that are not culturally correct (Kennedy's "Ich bin ein Berliner" example) or if there are highly controversial statements made that could rub either of the publics the wrong way, it's not a bulletproof thing. There is always the chance of it back-firing, though more with actual public diplomacy than basketball diplomacy we definitely hope not.