How do you become a better evaluator?

[Andy]

I am finding myself doing more observing and evaluating of umpires lately.

Especially with our fall season coming up, I am wanting to start identifying umpires to be considered for big assignments next year.

I feel comfortable evaluating on the basic mechanics and postioning, stuff like that..what I am looking for help on is what things do I need to look for to differentiate upper tier umpires from each other?

When you have some of your best working a tournament, what sets some apart? What are some little things to look for?