I think that it means that in the season of 180 games, the red team has the probability of winning each game of 0.55, so the expected number of games that the red teams wins is 0.55 x 180 = 99 games.
Since the blue team has a probability of 0.60, the expected number of games that the blue teams wins is 0.60 x 180 = 108.
So, the blue team is expected to win 108 - 99 = 9 more games.
Since the percentages don't refer to the same team, the percentages do not have to add to 100.