It's all mental. He's humiliated that Zverev has overtaken him and he's panicking. Also, for whatever psychological reason he CBF doing the work required to a) rehab injuries and b) avoid them.
I wouldn't say humiliated, but I get what you are saying. I don't even know whether zverev even figures much into his "issues", it is more like some performance anxiety he has talked himself into.
I'm hazy on the timeline, cause I don't follow him all that closely this is just my impression, I reckon the loss to Fed at the Laver cup wasn't just a loss, but damaged his circuitry in some way, so he re-grouped, started the year strong, won at Brisbane, but media and his own expectation for a dominant display at the AO was all too much, and he blew yet another circuit board, and he's been fried since then, too scared to play tennis, you can almost see the windows error code scrolling through his eyes.
He doesn't care enough to professionally dispatch low ranked opponents in early rounds, like Fed would, yet implodes completely playing big names in later stages. I don't think he should have lost to dimitrov at all at the AO, nothing against grigor, but he is over-rated for starters and was playing crap at the start of the year to boot. Kyrgios should have swept him from the court, but instead it was all too much, and he system 32'd, and has been on a terminal decline ever since
He's right in one way, if both of them were to be playing well, kyrgios WOULD beat zverev 9 times outta 10 imo, but zverev keeps getting back on his feet and trying, but St.Nikolas doesn't.
edit:
I mean, look at Blake, that guy broke his friggin NECK, then got leprosy or bubonic plague or something, then his dad dropped dead, plus even more I can't remember, yet he STILL gave it his all. Maybe Blake would be a good coach for nick, or even just give him a blood transfusion.
