If the team I covered all season had made it to the WCWS, I would have worn shorts.
I covered regionals and the first day I showed up in my usual attire of polo and slacks and noticed every single member of the sports information staff, every single radio guy, every single TV guy and every other reporter in the press box was wearing shorts. The next two days, I wore shorts with my polo. I would never do the sandal thing, but I don't have a problem with shorts at an outdoor/hot event, as long as you still look professional.
I'm trying to remember if I wore shorts at some point during my trips to Omaha, as well. I went there three or four times and spent anywhere from 3-10 days there, so I'm sure I wore shorts at some point during the event.