To answer your initial question, no, I haven't figured out exactly what triggers progression bumps. In Melendez's case, however, I'd like to point out that you most certainly did miss it. Clearly he gained a substantial amount of Charisma with this latest bump. Pretty big deal, I'd say. More importantly, he's 3 inches taller and 1 pound heavier than he was last season. The kid is well on his way.