Liverpool have failed to keep a clean sheet in this year's Champions League so far. This is partly down to their style of defending, where the strikers and midfielders are the first and second lines of defence. Last year, Liverpool had the best defence in the Premier League due to their coordination in playing the offside trap as a defensive unit together, and due to some fantastic saves from Alisson Becker. We are yet to see that level of excellence from the European Champions so far.
Liverpool's main source of creativity this season has been from their full-backs. In doing that, a lot of space is provided to the teams who have got runners willing to exploit the space and create attacking situations. Manchester City exploited this space in the Community Sheild fixture earlier this year.
Specifically in this game, Liverpool had most of the possession. This meant that Napoli had chances to go long and provide the ball to runners like Dries Mertens and Hirving Lozano whenever they got the ball. Dries Mertens was very smart in not letting Virgil Van Dijk win the long ball challenge and was first to the ball. Liverpool also failed to play the offside trap, leaving Dries Mertens one on one with Alisson Becker.
To their credit, the Reds have bounced back after conceding silly goals. But to expect that Liverpool can grind their way through the season by coming back all the time from unfavourable positions is not ideal and logical. They need to balance their attack with a system that provides for adequate defensive cover.