Jose Mourinho runs a tight ship over at Stamford Bridge, and an essential part of Chelsea's success in capturing the Premier League title last season was his employment of a consistent lineup anchored by experienced players on each line.

There was captain John Terry on defence, Cesc Fabregas in midfield and Diego Costa at forward. For the start of his debut season with the Blues, Costa was benched in favour of Chelsea legend Didier Drogba. But Costa's breakout performance, in which he scored seven goals in his first four games in a Blues shirt (including a hat-trick against Swansea), soon saw him promoted to a regular in Mourinho's formation.

As the new season approaches, however, Costa has been plagued by the return of a long-running hamstring injury, and will miss the start of Chelsea's title defence. Mourinho has said he is unsure of when the Spaniard will be able to return, Mirror reports.

With the striker's future hanging in the balance, we take a look at how Chelsea would have fared without Costa last season.

The 26-year-old netted 20 Premier League goals, the third-best in the league. Costa's total accounted for more than a quarter of Chelsea's goals and also beat every other Blues player, topping Eden Hazard's 14 goals.

Costa's high goal yield may be due merely to the amount of chances he takes. He averaged a team-best 2.9 shots per game, about 48 percent of which were on target (again, a team-best).

Summary of what we've learned so far: without Costa, Mourinho's side would've been missing a quarter of their goals and their most accurate hit man.

However, only two of the matches in which Costa scored resulted in Chelsea winning by a margin of less than two goals, meaning that his greatest contributions didn't come in moment where the Blues technically needed a winner. In other words, he isn't the most clutch.

No matter how you look at it, though, Costa is surely an asset that was a key part of Chelsea's title quest, and one who will be missed at Stamford Bridge should he not recover this season.

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