Are you running Ali Aintrazi's maindeck as well?
You've certainly played more games than me so take what I say with a pinch of salt. Still I'll say that if you haven't tried
Atzocan Archer you absolutely should - the card is really good against any x/1 creature (i.e. monowhite, monoblue and even monored). Even if it doesn't kill something on entering the battlefield it's a 1/4 blocker with Reach. Biogenic Ooze is also great as a sideboard threat and it can single-handedly win the game. Getting removed isn't that bad, you still got a 3/3 out of it and possibly more if you have Wilderness Reclamations out and can sink more mana into it.
I haven't played against control but it doesn't seem that bad on paper: you have tons of CA spells & some maindeck counterspells, they have loads of dead removal, and you have Hydroid Krasis with its cast trigger. After board with 4x Negate it should get even better. Carnage Tyrant and Nezahal might not be necessary.
If you haven't seen it, check out the decklist from the top 8 of GP Memphis, which has one Simic Nexus deck:
https://www.channelfireball.com/grand-p ... eck-lists/Running something similar to his maindeck yeah, can't remember offhand what I changed. Archer does seem ok, worth a try for sure. Not convinced that ooze is better than either tyrant or nezahal in the games where you'd bring it in, maybe against Eldest Reborn but Nezahal dodges that too.
I think control is much tougher than you suggest, especially post-board. They have access to a lot of disruption and card advantage, the game can turn into a war of attrition very quickly where who can flip azcanta becomes the main focus of the game. Generally, if they realise that's what the game is about, the control deck has more ways to deny azcanta. Of course there'll be games where they don't draw the right cards and reclamation just resolves and isn't instantly removed - but let's face it control decks are pretty good at not letting important things resolve
Nezahal is so strong against them, uncounterable, draws cards, protects itself from everything and puts out 21 damage in 3 turns. And no-one is going to name it with ego.
Blame Arena to be honest. I have to have full control turned on so often, or it just goes right through my Wilderness Reclamation triggers.
Don't need full control, just manually set a stop on your end step (you have to do this every turn, because I dunno, persistent stops are arcane technology or something).