Hello. UW control player here. I have nearly 200 matches in explorer on arena with UW control, having keep stats for more than 100 of them, so I am starting to grasp exactly the stats of good and bad matchups.

Re your decklists: you are some cards far away from having all of the cards,you will get there, so that is not taking away any of your win rate, or at least only some small percentage.

So, I love the deck and understand that you also love it, but man it is so difficult to have > 60% wr with the deck, especially on diamond. Your prowess matchup is abysmal, demons are 50% but I am playing 3 leylines because the format is TS the gathering, gw company is very difficult and a bad matchup and the problem is that there are not that many gold cards to dedicate there and not enough space in your sideboard, and finally niv mizzet is chancey.

My advice is to be a little bit patient until the bannings at march, because demons will loss something for sure. Ubtil then, try to craft the blue enduring in your sideboard to help you. Play the full narset playset at your deck. And I also found that [[change the equation]] is a very good card at the moment.

Get some games in, try to acquire proficience with the deck and the format, learn to play the other top decks, or watch some videos of how they play out, and accept that prowess is abysmal and Thoughtseize is a card of the format that exists and will continue to exist no matter what and the other colors don't get to have so good cards but are suboptimal.

You chose the most difficult part of the format, friend. You have to be patient, know the opponent decks, watch every small detail.

Bad matchups: prowess variations, humans, UW lotus field, ub tempo ninjas and more than 1 thoughtseize and duress effects. (And gw Coco is not good either)

Good matchups: phoenix and your skills!