Trying to slowly catch up on a lot of the forum posts I missed while away...
It seems as if once you engage in combat you are basically stuck in place, until you either destroy the unit you are fighting or he destroys you.
You don't have to destroy him to become unstuck, if he blinks first, and tries to withdraw during movement phase, he puts no ZoC pressure on you and you're free to break off as well if you want.
Or if he's determined to stick it out, and no one wants to blink first, the moment you can get at least 2 disruptions on him, he'll be forced into an auto-withdraw and again, this leaves you with no pressure from his ZoC, even if he fails to break off, you got him dead-to-rights since it's unlikely for him to shake off his disruptions while adjacant to you, unless you end up doing something similar.
Units at level 2+ disruptions are not going to pin you, and as a side-note, when enemy tanks come at you, you can try to put a river between you, which negates his ZoC from spilling over the hex-sides.
Anyhow, back in the day anyone who didn't think of E-ZoC in ladder clubs was not destined to advance very far up the rankings. All the top players would look at movements as PINNING. Either you want to pin him, or he is going to pin you. You want to pin a key unit(s) to either prevent them from aiding other units, or you want to buy time to bring up other units to take it out at a favourable exchange rate to you.
Sometimes you'd get two top players who were not even sure who was the one doing the pinning anymore... eventually it ends when someone rolls bad/good and someone blinks and then ..... well, someone gains another win that month for 6 more points to get a medal for top player of the month.