Sick>Victor and Asuna purely because of ability to agent flex. While Asuna and Victor are better duelists, Asuna only plays duelist and Victor isn't that good on other agents. If Asuna or Victor have trouble fragging, they aren't very useful to their team, whereas Sick can play Sage (or sova on icebox) if he needs to
Not necessarily, although it is harder to contribute a lot to the team as a duelist if you're having a slow frag day, so that ability to fall back on a different agent is a huge help to a team. Kind of like when 100T dropped Dicey so they could agent flex. Basically, It's not specifically because their playing duelists, more the inability to be useful in different ways