Put it into perspective though. Its one thing to skip a bullpen session, or practice, but a game is a game. Have you ever called out sick on a day when you were making a big presentation, or had an important meeting to go to? He only has to go out there one day a week, maybe two. If I had a job that only absolutely needed me once a week, in front of millions of fans, I would show up that one day a week.
After his last start, Beckett complained that "It's kind of been there for about a week, kind of leading into my last start," Beckett said. "On your start day, you can always make yourself believe that things are better than they are. I really wanted to pitch. I just ended up making things worse."
So, he's hurting the week before, and he skips his start because of the soreness... and goes out and does an activity that could potentially make it worse?