Dunno about all of them but sort of a 4/2 deal.
F6 are the special force of the Beast Pirates. In Wano only Drake (the head) and Page One (the youngest) were sent for a mission (Soba Mask hunt). After the beating we never saw Page One until Onigashima and we just saw Drake (at Yasuie execution as security and in the prison to supervise Law).
Now, just to make an example by rewriting a lil portion of the execution, what if instead of Drake and Hawkins (as security officers of the execution) were placed Drake and Who's Who, while Hawkins was just scrutinizing around Law? Hawkins didn't intervene at the execution anyway and was only searching for Law anyway. So, since his important scene was on the back of the prison, could have Oda just let him go with his hunter/sneaky thing and let one place free on Drake's flank?
Who's Who could have been there as the second security officer, maybe even giving us something to think about (in character for him).
While Drake looks at Yasuie above him, Who's Who looks at the bars behind him, grits his teeth and thinks "Dirty old days..."
Something like that would have been enough to give him an introduction. Yeah, Zoro would have still gone for Orochi/Denjiro and Drake would have gone for Sanji and Who's Who could have been the perfect 3rd man plus who makes the situation really shitty.
Strawhats had to retreat anyway, that would have at least given us more tension, hype and questions.
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A brief scene could have been given to Ulti, something like:
While Drake is reporting that he didn't arrive in time and Soba Mask was already gone, Ulti is showcased while tugging and insulting Page One (who's injured) for being injured
This would have showcased her status as the hot-head-big-sis briefly, leaving us with only 2 characters (Sasaki and Black Maria) to discover starting by 0 in Onigashima.