That was the original plan, actually. What changed my mind was that fighting disciplines begin to get mechanistic. That is, maneuver A will always defeat maneuver B, if executed correctly.
So it should be possible for one combatant to stymie his opponent's maneuver, even if he can't execute it as flawlessly or precisely. He just needs to be able to identify the maneuver used against him and its remedy.
So that's the Knowledge check, with the DC based on the obscurity and/or difficulty of the maneuvers. The execution of the maneuver is played out in the attack rolls. Allowing the players to set the DC themselves gives them some idea of how difficult their maneuver is, and how likely it is of being countered.