Hey dweebs, late to the episode thread here, but I couldn't help but point out what no one else in this thread has really hit on the head yet which is that in a completely different episode Ellie Kemper really didn't know how to play along. Some facts about Ellie Kemper to support this theory:
1) She's never done improv before
2) She's never done improv at UCB before
3) She's never done
s (and definitely not Neil Casey) before.
I think it's pretty safe to say these facts speak for themselves. This poorly trained actress who has never done improv, worked with the UCB or worked with Sean and Hayes before definitely did not "get" their shtick.