I think "they just play bigger" means that you have a higher make percentage at faster speed than you do at slower speeds. And this is obviously true since most top bankers use fast speed on most banks. Even mere mortals who haven't put in the playing time you guys have can improve their bank make-percentage with fast speed if they practice with it some.
For those interested, some of the reasons why fast speed helps make the "pockets play bigger" for banks are described on the advantages of fast speed banks resource page.
Regards,
Dave
Hmm, I would not have thought that's what it means. I would think it means "pocket speed" like Drop the Rock says above, or it means coming into the pocket at a more favorable angle - like coming straighter into the side pocket rather than at a sharper angle. That's different from "getting a more consistent bank angle" or some other aiming method that increases your accuracy.