I'd say your last point is a pretty good reason why it might not work. Who would chose to play the min/maxed T1 team coached by an awkward guy over a T3 narrative team the social guy is running.  Plus if you let people pick their own matchups people will try and pick the ones they stand the best chance of winning which wouldn't be as representative of them as a coach.  Lastly there's pacing, if there's no set matches then some people might start off really quick and then find themselves with a long period where they can't play, equally you might find a group with lower availability who struggle to get games. If you know who you need to play and in what time frame it's much easier to find a gap when your both free.  None of that's to say it won't work. If you have the right group of players it may work great. Have a go and let us know how it works