My ideas is that if an episode focuses on other characters and rarely features Elmo or doesn't feature him at all, THEN show "Elmo's World." If Elmo's the center of attention then there might not be any need to show it.
Anyways, the new Big Bad Wolf puppet doesn't look that great in my opinion. I know they got rid of the old Herry Monster-like wolf in the late 1980s, probably because he was too scary for kids. The purple wolf debuted maybe in 1987 or 1988, and I can't believe they are now switching puppets AGAIN. The wolf's voice was sort of goofy again and didn't sound right. Who performed him in this one? I'm guessing it was either Joey Mazzarino or Marty Robinson. Jerry Nelson did the best job with the Big Bad Wolf (and his twin Jackman Wolf!)
Oh, and I noticed another thing: at the beginning of each "Word on the Street" segment, they use the exact same clip of Maurice Monster every time! I bet it's to save money, like on "Inspector Gadget" when they'd show the same clip of Gadget reading the message in several episodes (mostly in the first season).