Frank Lampard’s Chelsea have had a topsy-turvy 2019-20 Premier League campaign. The young Blues have been one of the most exciting teams to watch this season, however, the players’ immaturity and lack of experience have also come back to haunt them on several occasions. After their latest draw against a struggling Arsenal side, we take a look into the five major problems Lampard needs to address at Chelsea. Lethargic left-backsMarcos Alonso has been a peripheral figure in the Chelsea squad this seasonWhile Chelsea’s right-backs include their captain Cesar Azpilicueta and another star-in-the-making, Reece James, their left-backs Marcos Alonso and Emerson Palmieri have often attracted criticism. Alonso, who was a prime asset under former manager Antonio Conte, has not replicated his attacking exploits under Lampard. And Emerson, who has a more defensively rigid approach, has also been subpar throughout the season. Lampard quickly recognised the team’s fallibility at left-back and deployed Azpilicueta there with James marauding the right-wing. The positional change did provide temporary relief for the manager but the 20-year-old Englishman’s injury meant that he had to start Emerson against Arsenal on Tuesday. Emerson's costly errors-in-judgement meant that Chelsea blew two leads against ten-men ArsenalChelsea fans slated the Italian full-back for playing the culprit in both goals Chelsea conceded against their London rivals. Even Lampard singled him out for his positioning error which led to Gabriel Martinelli’s solo goal.Catch him if you can 🏃‍♂️Anyone else still watching Gabi's goal? 🤩 pic.twitter.com/K1P3toMJ4o— Arsenal (@Arsenal) January 22, 2020Lampard said,“We have people on the edge of the box that ran forward when they should have run backwards. It left N’golo, it went to N’golo and he slips. That wasn’t the error. That’s something that can happen. The edge of the box was the error, as I say, a job that should have been done but not done.”Alonso, as we have often seen, can be extremely effective in a 3-4-3 formation, but his defensive vulnerability and lazy tracking back often sees Chelsea leak unnecessary goals.Lampard, hence, may have to resort to the summer transfer window to rope in a world-class left-back such as Leicester City’s Ben Chilwell, otherwise there could be serious implications for Chelsea on that particular flank.