I think they are just used to the premier leaguestyle of playing... they tend to perform better in premier league maybe because they've studied almost each team pattern and style of playing by competing with them frequently...on the other hand they are not used to the Bundesliga style that's why champions league is a hard one because it brings together different league teams with different playing styles
Playing against Bayern Munich doesn’t mean that they’re playing against the German style of football. Every team in the champions league have a great technique they use to play different and better than what they use to play in their domestic leagues. Arsenal needs to improve their game pattern in the champions league before they can be better and be so great to stand other big teams in the competition. If they don’t they’ll continue to be failing to bigger teams that are playing way above them when they meet in the Champions league
Real Madrid will be the strongest team for the Champions League next season. Bayan munich has a lot of problems, they won't be able to do so well at least in the Champions League with these problems. Manchester City lost many players last season on the contrary they didn't buy any significant players so if they don't buy players this season they won't do very well in the Champions League tournament. Real Madrid's XI was weak last season but this season their XI is absolutely clean. Real Madrid has good quality players in every position in the team now, so I can definitely say in advance that they will do well in the Champions League tournament next season.
Don’t underrate the Manchester City team. With Real Madrid squad including the addition of players to the squad, it doesn’t conclude that Manchester City won’t stand a chance to win the champions league too. It is a very competitive tournament and every team always showcase their best in the competition. Manchester City still remains on the same level with Real Madrid and I won’t see any difference between them for the fight of the champions league trophy. Other teams like Bayern Munich also can be so deceiving and look like an underdog to be feared for next season. The race has not yet began, so let’s wait for it to begin to have a better result on who will win the Champions League trophy.