Crate training for sport dogs tends to get lumped into the "basic life skills" category, something dogs are expected to already know before they ever step into a trial environment. But when you really look at what's happening at trials, the ability to relax in a crate is not basic at all. It's a performance skill, and for a lot of dogs, it's a missing one.
If your dog is pacing, whining, staring at everything going on, or staying in a constant state of arousal between runs, that's not just a crate issue. That's something that is going to follow you into your warm-up, into your start line, and ultimately into your performance. The crate is just where we see it most clearly.