Buster Posey is Craigslist. He always does what you need, is generally indispensible, holds the whole thing together, and works so well you forget he's there half the time. He also makes a shitload of money but doesn't lord it over you by having fancy parties or buying expensive shit.
Pablo Sandoval is Facebook. He's fucking huge, has questionable internal policies, and you have a love/hate relationship with him. He also brings in a shitload of money. And when your parents discovered him, they immediately became annoying about him.
Jeremy Affeldt is Zynga. It seemed like a good idea to give him a lot of money when everyone was talking about him, but now it's kind of embarrassing and he's steadily tanking and you don't want to be seen playing him.
Hunter Pence is Twitter. He's out there every day, you check in on him a lot, and he's sometimes amusing, but he doesn't really do anything.
Tim Lincecum is Yahoo. He used to be vital and important to your life, but now he's not very useful and actually kind of embarrassing and actually you'll be sorta glad when he's gone.
Matt Cain is Tumblr. You loved the shit out of him, and when he was on, he was fucking GOLDEN, but now that he's gotten a huge payout, you're kind of worried about him.
Barry Zito is Windows. He makes an ungodly amount of money and only works about half the time, but now we can't get rid of him.
Sergio Romo is Apple Maps. He was great for a while, but then we made some big changes to him and now he just fucks up a lot.
Jeff Francoeur is Blackberry. He's washed up and was never that great to start with, but you bought one on a whim because, who knows, maybe it'll work this time.
Mike Krukow is PandoDaily. He unquestionably and relentlessly praises all the people who pay for him.
AT&T Park is Apple. It's severely overpriced but we keep buying it because it works pretty well and we have a lot of brand loyalty.
UPDATE!!!!!!: Chad Gaudin is Redtube.