Former RB Leipzig manager Jesse Marsch has insisted that Roberto Firmino remains an important player for Jurgen Klopp's Liverpool side.Marsch, who managed both Red Bull Salzburg in Austria and RB Leipzig in Germany, remains a huge fan of the Brazilian international despite a significant dip in his numbers. The American manager sees Firmino as the focal point of the Liverpool attack and insists that the ex-1899 Hoffenheim man makes Klopp's forward line tick.The 48-year-old wrote in The Athletic: “As RB Salzburg coach, I faced Liverpool three years ago and Firmino was the key. It’s because of his flexibility. They play 4-3-3, but with the ball, it’s more of a diamond when Firmino is there because he drops deep. He tends to run the most out of anybody in the game."Firmino has often attracted plenty of criticism over the last couple of years for his lack of output in front of goal.Rol@lfc_ralUnpopular opinion: Mané Salah Firmino is the best attacking trio in premier league history10:37 AM · Feb 10, 202235022Unpopular opinion: Mané Salah Firmino is the best attacking trio in premier league history https://t.co/dYrqP75EQIThe Brazilian's struggles for goals and assists have continued this season. He has just seven goals and four assists to his name in 23 games across all competitions.Diogo Jota's goalscoring form has often seen Firmino settle for a place on the bench but Marsch feels Firmino is still an integral part of Klopp's system. The former New York Red Bulls manager also believes that Mohamed Salah and Sadio Mane greatly benefit from playing alongside the 'clever' forward. He continued: “He’s clever with combinations, he sees things but still has the ability to get in the box and be dangerous. Salah and Mane are so entertaining, so explosive but it’s often Firmino’s movement and connection with the team that allows them to have more room. Firmino comes away from the centre-backs and that allows Mane and Salah to run in behind.”Liverpool have a wealth of options in attack The trio of Firmino, Salah and Mane was once regarded as one of the deadliest attacks in Europe. Liverpool now have much more quality and depth up front outside the three.Diogo Jota has been one of the best players in Europe this campaign and the arrival of Luis Diaz also adds a great deal of quality to Klopp's side.Anfield Watch@AnfieldWatch30 goals in 61 appearances 🤯 @DiogoJota18 2:19 AM · Feb 15, 2022306520230 goals in 61 appearances 🤯 @DiogoJota18 https://t.co/k6ZAyV5cPSThe likes of Takumi Minamino, Divock Origi and Alex Oxlade-Chamberlain might be fringe players but they have also delivered when given opportunities.Wonderkid Harvey Elliott's return to fitness is another major boost for Klopp's side as the Reds look stacked up front.