The wording of the change sounds like it will cause *more* mobs to loose engage status, thus regaining health faster. Your anecdote about stun locking the infinity spawn sounds like there are fewer mobs that loose engage status, so they die faster now. In other words, before the patch the stun locked mobs never had engage status set, and were therefore regaining health faster. And now this patch means that they all have the engage status set during the fight, and are now dying faster. So I'm not sure I see clearly what's going on yet.
it means they're not waiting for some effect to wear off before they decide if they're in or out of combat.
Oh, I see. You stun them from outside of agro range? No wonder I couldn't ever get a handle on stun locking the infinity spawn. I've just been taking war/brd/dru, and cranking up the Damage Shield. Slightly longer fight, but fewer apm required. That makes more sense now.
I give a TL window to a cleric who runs them off with DA. I then install the enchanter within stun range and cast minor illusion. When they come back, their tiny little eyes don't notice the extra bucket. This means the first cast on the mob is a stun, which was causing them to be out of combat until this patch.
not really possible to pbae stun outside of agro range, considering stun range (35) is smaller than agro range (50)
While the illusion trick is the easy way, it is actually possible to stun them from out of aggro range. It's practically pixel perfect, but I messed around with it for no particular reason when AEing there before, and Color Slant does reach ever so slightly farther.
If a Necro dots a rooted mob(not rooted on spawn point) and FDs, the mob regens as if out of combat while also taking dot damage, is this intentional?
That's expected behavior; if you're FD and nobody else is on the mob's hate list (and in pursuit range), it's out of combat even if it has a dot or debuff on it.