That is the verdict of former Blues captain Paul Elliot.
Boss Antonio Conte has bemoaned his squad size after missing out on numerous transfer targets throughout the summer.
Alex Oxlade-Chamberlain, Fernando Llorente and Ross Barkley are just a few of the names who turned down the chance to move to Stamford Bridge.
And Elliot believes Manchester United and Manchester City have a better chance of winning the league due to their squad quality.
"It is very interesting for Chelsea because they have a brilliant 13 or 14 but it's about the strength in depth," he told Sky Sports.
"You look at Manchester United, you look at Manchester City and what is the common characteristic? They have got the strength in depth.
"It's the quality of their substitutes that dictates a lot.
"Chelsea are going to be competing, they are going to be taking points off all of the teams around them, but I think ultimately the teams with the deepest squads - Man City and Man Utd will be very close [to winning the Premier League title]."
Chelsea battled back to rescue a 3-3 draw with Roma on Wednesday evening.
During the clash, manager Conte cut an uncomfortable figure on the sidelines.
Speculation over the 48-year-old's future at club has been rife due to his desire to return to his native Italy.
