It's gratifying if a team has a good pair of full-backs, but Chelsea have two equally capable players on the left flank, Marcos Alonso and Ben Chilwell, and it's a shame and a luxury to put anyone on the bench.
Marcos Alonso is not a good left-back, but he is a left-wing defender in the top five in the world. The 30-year-old Spain international is not fast, but his air superiority, timing of the back-up cut, shooting skills, and sense of position are all quite outstanding. Under the protection of the three-centre-back system, his lack of speed can be handed over to Antonio Rüdiger behind him, allowing him to insert assists with peace of mind. Marcos Alonso is a great threat in the penalty area, because his left-foot shooting ability is quite superb, basically any position, angle he can find the opportunity to get up; at the same time, his height advantage also makes it easy for him to get the air supremacy on the left side, as long as the cover is appropriate, Marcos Alonso is definitely a good wingback.
Ben Chilvey's strengths are not the same as Marcos Alonso's, both are full-backs with strong defensive ability, speed, ability to play with teammates, and crosses. Compared to Marcos Alonso, Ben Chilwell is more of a left-back. The England international has no obvious shortcomings, his cutting ability and shooting skills are not as strong as Marcos Alonso's, but his crosses, the touch of interacting with his teammates on the left are even better, and last season Ben Chilwell also delivered excellent attacking statistics, four goals and seven assists in 42 games, which is Chelsea's highlight of winning the Champions League.
However, this summer, Ben Chilwell was called to the national team by Sosgay but did not get a chance to play, making it difficult for him to maintain his form, and he failed to return to the team to train at the earliest time (because England played until the last moment of the European Cup), which disguised marcos Alonso, who was not a regular in the national team, to push him back to get the right position. This season, Marcos Alonso has nine appearances, a goal and an assist, while Ben Chilvey is a temporary vice-pick, but also has four appearances and a goal.
After Ben Chilwell gradually regained his form, it is believed that Thomas Tuchel will be even more distressed in the platoon, because the performance and strength of both men are worthy of the right position, and see how the German manager will make a trade-off.