Hey, way to get back at it! 
I can relate to that. I cringe now at “functional.” There are people/things that work and those that work well. In the end, I was not the latter.
The thing about still performing at work is it can become mechanical. I could still do certain things because I’d done them so often they were muscle memory. Given enough time even those started to suffer.
What changed for me was realizing the motions became devoid of any meaning outside of what they offered me. I’d get up, do the deal, tend to the house, then embrace the blackout. I had very subtle but powerful fears of contributing to anything more.
From this forum and the rooms of AA I quickly woke up to where that was going and what I could have back if I just shook off the drink and started living to live again. I tried whatever I saw working for other people who’d been where I’d been.
Still not always sure where life’s going, but today the momentum has completely shifted and the prospects are much brighter than they were this time last year!