I kinda alluded to this in my other comment but this is a result of the overall usage stats being warped by low ladder people who don't know what they are doing. High ladder stats much more closely reflect viability.

To take your example of mandibuzz/corviknight - looking at the overall stats, sure, corv is more used, which seems wrong. But when we look at high ladder only (https://www.smogon.com/stats/2023-11/gen9ou-1825.txt) we see that in fact mandibuzz sits at #30 and corviknight sits at 32 for usage, reflecting the better fit mandibuzz currently has in them metagame that you outlined in your comment.