Do people select proficiencies Skirmishing, Combat Trickery: Overrun, Knockdown and Force Back? I don't think so... I think they should be combined into one proficiency, possibly called Skirmishing... It cover all the "mobility" moves.
In addition, I propose modified mechanics for them:
Dynamic Combat Maneuvers
Attack throw is normal, modified by +2 by the new Skirmishing proficiency, against a modified AC given by computing:
Level bonus: 10-Defender's Attack Throw (so a 5th level fighter, with Attack throw 7+ gets a 3 here).
Compute Physical Ability: Maximum of Str and Dex bonuses minus Minimum of Str and Dex penalties. (As with strategic ability).
MAC = Level bonus + Physical Ability + Allowed Modifiers
Allowed modifiers include those from graceful fighting ability, swashbuckling, magic items/spells "of protection" and spells that improve AC through luck, speed or divine favor.
Once the initial roll is successful.
Effect Damage roll: Die type is d4 for Fighting 0 classes, d6 for Fighting 1 classes, d8 for Fighting 2 classes, d10 for Fighting 3 classes. Modifiers for strength and other class abilities are allowed.
Force Back: On success, opponent is pushed back by a number of feet equal to the Effect Damage dice. Opponent can save vs Petrification to halve distance. Being pushed into things is handled as in the main rules.
Knock Down: Opponent gets a saving throw vs Petrification to stay on his feet as in the main rules. Opponents being Knocked Down by a Force Back get a saving throw vs Petrification to keep their feet, as well.
Overrun: Opponent gets a saving throw vs Petrification to get the ability to block. Success on this saving throw allows opponent to stop progress, but opponent automatically takes Effect Damage roll in damage.