Eh, Oregon doesn't have the quickest players either. Minyon Moore and Destiny Slocum are both pretty quick. That'll be the quickest matchup on the floor, both are the quickest for both teams.
I don't categorize Ionescu as "quick," either, at least not on the same level as her skill, competitive nature, and IQ. I would say she and Pivec are on a similar level of athleticism, Ionescu is just a better ball player.
Boley is definitely not what I would consider quick. Sabally moves extremely well though, and has an amazing first step for 6-4. She blew past Napheesa on multiple occasions. She has been a matchup problem for OSU in the past.
Maybe Ionescu isn't the quickest but with her angles and positioning she seems to be quicker.
And Sabally used that first step to give Miss State fits also.