Like you said, on the 2 minutes I thought of this topic, the only way I can see it being functional is: You bring (15?) candidates to choose from. Your opponent chooses (5?) to ban. You try to create a cohesive team from the (10?) remaining. Fill it in with whatever numbers you want. From that pool, players ban out the most versatile options you have, limiting your ability to create a cohesive team.
I don't find it terrible in concept, it's just.. a completely different game to what we have now, but with the same problems. You still lose in the "draft", you're just hoping you get lucky and the opponent misplays their bans so you can create the strategy you want. And if the issue is "grind" like the second post said, then I'm failing to see how it actually addresses it, and why this approach would be better than cutting out the middleman and just introducing some form of rentals for players who want to skip straight to PvP.