No candidate moved outside the 2% MOE in the poll taken the day after the debate.
Biden: 31% (-1)
Warren: 21%
Sanders: 18% (-1)
Harris: 7% (+1)
Buttigieg: 6% (+1)
Yang: 3%
Booker: 2%
Klobuchar: 2% (+1)
O'Rourke: 2% (-1)
The poll, which surveyed 2,202 registered voters who indicated they may vote in a Democratic primary or caucus in their state, registered less movement among the race’s top contenders than was seen before and after the previous debates in June, July and September."
The viewership was down presumably because of the baseball game although maybe people are tired of watching that number of people in a drive by 75 seconds answers and are waiting until the stage is set with a limited number of players.
Biden's first debate performance hurt him and Harris had her bounce but settled back to where she started the summer. The only candidate that moved up during the summer debates was Warren.
"Biden’s share of first-choice support has dropped 7 points since June 23, while Warren — who has received the highest average debate score in Morning Consult/Politico post-debate polling and went into Tuesday night with higher expectations than ever — has strengthened her position by 8 points. Harris, who saw a brief spike in support after the first debates, ended the fourth debate essentially where she began the summer, while first-choice support for Buttigieg and Sanders has not changed during that time period. "
Morning Consult Poll