JWill is not what your sentence says he is. He has a very nice mid-range pull up game. And he absolutely likes to push the ball up in transition. Does he like to get to the rim? Yes. But his primary damage and effectiveness in the half court game was driving and pulling up for the 12-16 foot jump shot, and/or passing to open teammates on the perimeter (who then couldn't make their shots, FYI).
Also, JWill and Derkack are not really similar players, other than the "general" description of taller guards who are supposed to be good defenders and poor 3-point shooters. Derkack's game last season involved a much stronger emphasis of getting to the rim than did JWill's game. That is one difference - and we have no idea how that will play against Bug ten defenders who are much taller and more athletic than Merrimack's opposition. Also, Derkack did win Defensive Player of the Year in his conference, as just a sophomore ... to his great credit. But by his own admission he never played man to man defense, as Merrimack was essentially a 100% zone team. We know JWill is a very good man to man defender. Additionally, Derkack was a turnover machine - just a huge amount of turnovers per game ... while I saw a highlight video that showed his 3-point shooting, while not great, was over 30%, maybe even 33%, when he took open, catch and shoot 3's.
So ... the way I see it, JWill is actually more effective in a "lead" guard, with the ball in his hands, and as a 6'4" plus man to man defender, with a solid mid-range game. Derkack will be a willing defender (though how good in man to man remains to be seen - I trust Pike to teach him well), will push the ball in transition (he is athletic - and 6'6"), but better as a Wing Forward reserve, getting to the rim, and receiving kick-outs for shots from the Wing ... not a "lead" guard.
I will bet dollars to donuts that Derkack is the primary back-up at the "3" when Bailey rests, or when match-ups suggest Bailey to the "4". Acuff will be the 1st GUARD off the bench - and is NOT a PG at all, but an offensive spark off the bench for either JWill or Harper - or both. Can Acuff play on the court at times with both Harper and JWill? Yes. And Davis becomes the 2nd guard off the bench, for his ridiculously good defense and solid rebounding for his size - and his ability to push the ball up the court in transition ... While he does have to improve his decision-making, he IS the quickest and fastest RU guard with the ball in his hand in transition.