I think Mary's talkativeness is indeed nervousness, but I think she is valuable as a counterpoint to her mom's style --which sometimes comes across as too rigid or uptight . Maryann can be "all business" while Mary is more relaxed which can lean toward quirky. But hey, I have learned from both of them. I enjoy Maryann's straightforward teaching style but appreciate some humor injected. Liz definitely offered both and I miss her.