Has his game really regressed or was it just never that strong to begin with on the hard courts used at the AO and the USO? He got a huge break when Djokovic didn't play the US Open 2022, and then his draw really opened up for him (Nadal lost early, Meddy lost to Kyrgios, who then lost to Karen, Zverev missed the tournament with injury, Tsitsipas lost in R1, Sinner was a year or so away from hitting his stride). It wasn't easy by any means, but he went five sets three times in a row and the only player he faced ranked in the top 12 was RUDD.
The Calf is certainly a very good player on the courts used at Indian Wells and in Miami, but I think the jury is still out at the US Open and certainly at the Australian Open.
Also, note these things about RUDD's hard-court resume:
1) Apart from at the 2022 US Open, he has never been past R4 of a hard-court slam. (He has made the semis of RG three times).
2) Only one of his 13 career titles is on hard courts. (The other 12 are all on clay).
3) He is trying to sandbag a title in Gstaad this week, where the second seed is Bublik, who is probably not going to be as dangerous on a slow as molasses court as he was in Halle. RUDD's route to the title is: Stricker (he beat him 7-5 7-6 today); J-M. Cerundolo or Goffin; Burrachaga or Buse; Bublik or Etcheverry (the latter of whom has never won a career title). This isn't relevant to my post, but I have been meaning to comment on it somewhere and this felt like no more irrelevant a time than any.