Why does the supercomputer keep changing its mind about the Premier League title race?

Man City now have a 70% chance of winning the title - but last week it was 40%. Why didn't the computer know what was coming?

Why does the supercomputer keep changing its mind about the Premier League title race?
Man City now have a 70% chance of winning the title - but last week it was 40%. Why didn't the computer know what was coming?