In the current game, zombies are easy to kill once you get them into a stun-lock. This presents zombies as more of a minor inconvenience rather than something you should really be worried about, or even much of a challenge. A simple whack on the noggin leaves them defenseless.
I propose that the zombies should only be stunned when players use a powered attack, or when they hit a zombie in the head from behind. This would mean that for most situations, players would need to move backwards while attacking the zombies in front of them (just like the good old days). Powered attacks could be used to thwart some zombies further back in the case of a horde, and sneaking up on zombies from behind would be better rewarded by allowing you to stun them.
Although there should be some exceptions, especially with the runners and crawlers (and possibly some other types). If the runners weren’t stunned like they are now, then it would cause each engagement to end with you losing some health almost guaranteed. And in regard to the crawlers, the hard to hit angles in addition to not being able to stun them would make these guys a nightmare to deal with (just like the good old days…). Allowing stuns on normal swings for these guys would probably be best.
I would imagine that not all players would be quite on board or ready for this, so I’d apply the change to normal, hard, and gold only (stunning could even be completely removed on hard mode if Nelson is crazy enough). But I believe that this would best address the monotonous and boring stun-locking meta that we’ve become accustomed to, whilst also opening up some new strategy in regards to how you approach zombies.