Beginning with the All-Star Game last year and again with the NLCS this year, I've noticed whenever there is a big game, no one is allowed to sit in the last two sections of the mezzanine in center field. I know they do it for the hitters' background, but then why sell those seats at all during the regular season? There's times in the regular season when games are sold out and those sections are mostly full.
I know that they aren't great seats, but its still a few hundred more people that could get into the park though.