Cup games, so you propably were facing a manager one or two levels higher then you. Most likely scenario is that you faced a player who sold his whole team at the end of the season to buy a new team the first day of the season. By selling your best players in the end you drop like mad in the average rating of your team and get a better cup draw (stupid stuff) against low level players. He only keeps 1-3 star players who look like 5 star players to you because you are 2 levels lower. When he buys his new players (5 star in his level but 7 stars to you) he will rise in rating like mad.