In addition to the variations mentioned in the previous posts, different aircraft types will have different limitations affecting their performance: For example, based on the information shown in your post, jet aircraft were diverting, whereas turboprop aircraft were not.
Weather conditions will also vary from one approach to another, and also within the same approach.
Without monitoring each individual flight, it is difficult to know the precise reasons for decisions taken: It really is up to each pilot, within the established boundaries for each approach, and I'm absolutely relaxed about that - it's as it should be.
Hope this helps...