A note from that site:

His data is heavily weighted with pre-debate numbers:

Not a lot of change in the state polls right now. I installed new software
yesterday to average recent polls per state going back 30 days. There was a
create hue and cry that this was a bad thing because the race is in such a
state a flux that polls that old are meaningless. In the middle of the day I
changed the look-back parameter to 7 days, so now only polls within the past
week are used. I agree with many readers that 30 days is too much. If I were a
Republican, I would have said "I am going to stay the course, even though I am
wrong." Fortunately, I am a Democrat so I can flip-flop all I want. Let's see
how a 7-day look-back window works. The idea was to prevent the map from
changing wildly every day. Averaging introduces some stability, but also
introduces lag in responding to current events. Finding the right parameter
might be tricky.