This is ironic. I think he hates Andy Murray.
The first time Murray and Henman played on the ATP Tour, Castle was commenting and called it "a match between a fine wine and alcopops". AC has always adored Henman, and really resented this upstart Scot stealing Tim's thunder, beating his records, having Henman Hill renamed, etc. And to me he had a lot of trouble hiding it.
Nowadays he's much more aware of his audience's tastes, but if you listen closely there's still a darker undercurrent. He's very, very, very prone to employing the infantile "jinxing" technique that people like Clarky use when talking about Djokovic, i.e. Murray gets a set and a break up in a best-of-five, you're likely to hear Castle declare that "the match is over now" or some similar nonsense. He never does it with any other player, and I consider it childish and unprofessional to conduct himself like that. Judging by this thread though, it looks like most don't notice it.
I also find him not remotely knowledgeable compared to either his contemporaries (ex-players like Lloyd, Henman, etc ~ probably because he lacks any experience in the top echelons of the game), or especially the prior generation of old-school commentators (Threlfall, Barry Davies, John Barrett, Maskell, etc).
His early days were as a post-match analyst on the BBC, and he made me cringe from the start. Having failed to ever get into the top 100 in his entire career, I just felt he was out of his depth trying to offer insights on the top players. Alongside McEnroe and Becker he was grim, truly grim.
Regards,
MDL