I don't think the consequence option will work - at least not for Evocation. Evocation is basically an attack and the decisions about consequences is up to the defender. That is the defender decides if he wants a consequence and if so what it is.
For Evocation, I can see that as a take out - as in "I send him crashing to the floor, knocking the wind out him and taking him out of the fight".
Thaumaturgy allows you to put a specific consequence on someone... Assume an Endurance of fair, you would need:
6 to overcome the best Endurance roll that the target can make
3 to fill the target's stress track
2 for a mild consequence
For a total of 11
Or if you felt lucky and wanted to bet that he would roll 0 or less, it would only be 7. Seven is more doable in combat than eleven.
But the more I think about, the less being knocked down sounds like a consequence. Even a mild consequence has too long of a duration for "knocked down" to really apply, so it looks like a maneuver is the best way to go.
Richard