Defensive difficulty | According to the statistics of the Daily Mail, Chelsea coach Frank Lampard has tried 20 different defensive combinations in 41 Premier League games since he took office, changing on average every two games. Among them, the most used combination is Christensen and Zuma partner center back, Azpilicueta and Rees-James guarding the wing. This defense lineup has 5 appearances, conceded 9 goals, and completed 1 zero block. The second most commonly used combination is that the other three remain unchanged. Zuma replaced Rüdiger. This lineup has 4 appearances, conceded 5 goals, and also only had 1 zero cover. In addition, since the beginning of last season, Chelsea have conceded 42 goals in the league away, the highest among Premier League teams in the same period. While strengthening the attack line with a lot of money, should Chelsea focus more on the transformation of the back line?