Chelsea defender Cesar Azpilicueta has admitted that he is baffled by his side's inconsistent Premier League finishes over the past four years.
The Blues followed up their title wins in 2015 and 2017 with lowly league placings the season after, finishing in 10th place and fifth.
Having missed out on a spot in the top four last season, Chelsea - now under the management of Maurizio Sarri - are well on course to challenge for a third title in five seasons.
Azpilicueta, who has been at Stamford Bridge since 2012, is unsure why his side lurch from high to low so regularly.
"It is difficult to explain. We have been the club in England that has won the most trophies in the last couple of years," he told The Mirror.
"We are Chelsea we are fighting for trophies and we have to be up there and it is frustrating when you see we are able to win the title and then the next year we are not.
"I would like to be at the top always. It is difficult but it is our job and we have to try to do it."
Third-placed Chelsea trail Manchester City and Liverpool by two points ahead of this weekend's trip to Burnley.
