I'm not the biggest Simonsen fan, but he's an incredibly diverse, talented bowler, and he deserves credit for the decision making and shot making that won him another major title.
Now, as for Belmo, I'm sorry, but I don't see what happened to him as a choke in any way, shape, or form. For me, a choke is when you have a great look, but you mess it up because you're too amped up/nervous about the peripheral stuff. That wasn't the case with Belmo at all. He made a bad ball change, and he couldn't out-bowl it when he needed to most. I would have only looked at it as a choke had he aced the last 3-4 shots only to throw it out the window when he needed it most.
We have to remember that these guys, Belmo in particular, are the very best in the world. With that in mind, they honestly believe they can pull off whatever shot they need whenever they need it, and they feel that way because many of them have proven the ability to do it time and time again.
Think back to PDW's "Who do you think you are? I am!" moment. That was one of the greatest shots in the history of bowling when you consider what was riding on it. Even if I had Pete's look, I probably wouldn't have pulled that shot off because my mind would've drifted to the title, the money, the people watching, etc. THAT would be a choke.
I think Belmo picked the wrong ball because he didn't expect to be able to grind out a low 200 game win over a guy like Simonsen. He realized his choice was bad, but he felt like he could still make the shot he needed to win as long as he aced it. This time, he didn't ace it. That doesn't mean that he choked. It just means that nobody comes through every single time. Michael Jordan missed a lot of potential game-winners. What made him great was that he was just as confident he'd make the next one, and he often did. I think that Belmo will be just fine the next time he's up with a chance to win.