Billy Beane officially kickstarted trade deadline season on Thursday morning, shipping out lefty Scott Kazmir to the Houston Astros in exchange for a pair of minor leaguers.

As news of the trade began circulating online, Kazmir was in the A's clubhouse hugging his now ex-teammates and exchanging goodbyes before heading on his way.

The vibe in the clubhouse before Thursday afternoon's game with the Toronto Blue Jays was melancholy, as represented by this qutoe from catcher Stephen Vogt (as reported by MLB.com's Jane Lee): "I'm sure it's not going to be the last move. This is kind of a weird week in baseball for every team, because you don't know who's going to be your teammate tomorrow, who's not going to be. I got to the park thinking I was catching Scott and find out about an hour after I got here that I'm not. That's the way this game works. It sucks. He's a good friend, good person, good pitcher. When somebody that quality of a teammate and pitcher leaves, it's never easy."

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Said Kazmir to Lee regarding leaving the A's behind: "They were just messing around, calling dibs on everything. These guys, I'm going to miss."

Later on in the day, several members of the A's took to Twitter to wish Kazmir good luck with the Astros. He, too, posted a 'thank-you' to the A's and A's fans for the season and a half he was a member of the A's starting staff. Below, check out the Tweets sent by Kazmir, Sonny Gray, Sean Doolittle, Josh Reddick, and Brett Lawrie - and Kazmir's replies back:

Of course, due to Houston and Oakland both being in the AL West, Kazmir and the Astros will return to Oakland in a few weeks for a four-game series, maybe presenting the lefty with an opportunity to pitch against his old club right away.

(h/t MLB.com, Twitter)