If you want some perspective of bad commentating, have a listen to the modern pentathlon announcers during the equestrian portion. Some of the things they say just leave me scratching my head.
But I agree - there is firstly a difference between announcing and commentating. Announcing being what I’d expect to hear while I’m out walking the grounds as Willesdon mentioned. Commentating is what I expect to hear when watching things live on TV. I once announced for a barrel race competition, had a ball hanging out with people in the office, had a great view of the competition and I found it pretty easy. “That was a time of [insert time]. [say time again]. Joe Schmoe, you’re up. Sally Runsalot you’re on deck. John Doe, you’re in the hole. Jane Buck, be thinkin’ about it” Rinse. Repeat. Could I have commentated that same event? No way.
IMO a good commentator is someone who can balance explaining the basics of what the viewers are watching in a way that is sufficient for someone who has never watched it before, but isn’t so boring that people who are familiar with the sport are going to get annoyed by a 15 minute lecture of “kindergarten level” stuff.
They’ll be knowledgable enough to point out some subtleties (“this rider is taking a slightly different track to try and do X” or “this horse has a tendency to be Y and you can see the rider managing this by doing Z”). If they’re really sharp, they might know some history of the horse/rider and be able to mention how they’ve stepped up their game this competition or see how they’re focusing on things they’ve struggled with at past events. Even better if they can have a good sense of humor and they mesh well with their co-commentator while they’re doing it. I think most importantly though, the very best commentators truly want each and every rider to SUCCEED. They may offer some critique (hopefully not scathing, and generally lighthearted), but you know they’re still really rooting for you behind the microphone and cheering you on.
That’s honestly my biggest qualm with KOC - every now and again you can just tell she doesn’t like a particular rider for whatever reason and she wouldn’t be disappointed if their horse stopped on course. Conversely, sometimes you know there are riders she’s got a special interest in (maybe they rode with her for a time) and she really plays favorites with them too. Both scenarios irk me - I’m here to enjoy a competition, not get involved in barn politics.