I guess your problem with hat range is that he can afk under tower and usually have 100% uptime (never dies). It’s argued that such a playstyle is anyway not really reaching full aba potential…
I can see how fights could eventually get out of hat range, and force aba to relocate/ make the battle 5v4 for a few moments, but it wouldn’t change much, if any early game teamfights. It wouldn’t change any objective, since they’re all static. I feel it would only be a nerf to an aba that’s behind (a few towers down), while imo he’s already awful in losing games and feels too good in winning games.
I’d say the unfun mechanics are the 13-16 locust talents, attack speed on 4, and maybe mule on 7 (although mule is probably more of a skill check on enemy, wouldn’t say it’s OP)
I’d rather aba locusts get a mechanic similar to zagara buffing minions talent on 1: locusts could be stronger while he’s near, and weaker while he’s away (the minions don’t necessarily need a visual effect to know that aba is near though, I think that would be too big a nerf).
I’d go as far as make the locusts a little stronger (20% better than now?) while in close proximity (aba shouldn’t sit behind his own gate) but a lot weaker (50%? 30%? current stats) when aba is away; basically remove the landmine - teleport- spawn 3 locusts - B combo (or he sits there and dies for tower, i guess). Locust stats could ‘scale’ with distance, so it doesn’t instantly go from strong locusts to weak locusts.
And remove attack speed hat/ tie it to carapace shield at least, so poor AA heroes can finally be balanced without being broken with aba. If they removed old tass shield (and that lifesteal talent no one talks about, which was unique) they can dump the attack speed hat too.
Edit: I am surprised, given zarya gets a sort of shield-spam build, and medivh gets a ‘healing talent’ (reabsorbtion) why they didn’t give aba a healing/armor talent on carapace too (or a sort of ‘carapace build’). Or, he could be a ‘jack of all trades’, and have talents where he loses something and gains something else (like collosus smash changing hero stats). He could very well lean harder into hat and lose on locusts, lean into mines and lose hat power and so on.