How Oscar Can Prove He's an Ace in the Pack for Chelsea Once More

Has Oscar's Chelsea career been given the lifeline it needed?

Maybe.

The Chelsea midfielder has been forced to pull out of Brazil's squad for this summer's Copa America, tweeting to his two million followers on Tuesday that he was upset he couldn't represent his country in Chile.

He should be anything but.

As reported by the Guardian, Oscar's absence is the result of a thigh injury picked up in training, which has ruled him out of Chelsea's end-of-season run-in.

The Premier League title is now secure, so Jose Mourinho won't be too concerned that Oscar is unavailable for the next three matches. Looking ahead, however, the Chelsea boss must surely be contemplating how to tackle the midfielder's ongoing lack of form post-Christmas.

For the past three seasons we've seen it; Oscar has been exceptional in the first six months of the season, but when the calendar changes, he's forgotten as quickly as the New Year's resolutions of the masses.

Which is why missing the Copa America may well have rescued the Brazilian from Chelsea oblivion.

The theory behind this phenomenon has often been fatigue, that Oscar's schedule leaves him burnt out.

In 2012, Oscar represented Brazil at the Olympics, in 2013 it was the Confederations Cup and last summer the World Cup.

Paul Gilham/Getty Images

Since he joined Chelsea three years ago, Oscar has played 165 games for club and country, with little room for rest.

Even by modern standards, that's an incredible statistic (and one that doesn't include the six games in which he featured in the Olympics prior to joining Chelsea, when Brazil lost to Mexico in the final).

Oscar has shown enough in his time at Stamford Bridge to support the belief in his ability to play at the highest level in Europe.

We need only think back to his Champions League debut against Juventus and the two exquisite goals he scored that night. Not only that, but he did an excellent job in stopping Andrea Pirlo in his tracks.

Michael Regan/Getty Images

Too often Oscar has disappointed, though. When Chelsea have needed him most, he has gone missing. He's allowed Chelsea to carry him, and his influence has waned significantly.

Indeed, it's no coincidence that Cesc Fabregas' offensive stats have taken a hit at the same time Oscar's form has dipped this term.

As this Chelsea team evolved in the beginning stages of 2014/15, Fabregas and Oscar seemed telepathic in their understanding. They were switching roles at will in matches, the latter allowing Fabregas to venture forward at times, dropping in as cover.

It meant they were difficult to pick up and track, but without Oscar performing, it's meant Fabregas has had to adapt his game.

Paul Gilham/Getty Images

Mourinho's tactics have played their part in that, yet equally the manager's changed things at Stamford Bridge to suit the personnel in which he could rely upon.

Being hooked at half-time on numerous occasions and dropped from the starting XI, it's evident Oscar hasn't been one of those players.

With a summer's rest, a summer free of football and continental travel, Oscar's been given a rare opportunity: to prove us right.

Has it all been burn out? Is he playing too much football? Does he have the stamina and ability to last a full campaign? Can he be the No. 10 that Chelsea have lacked since January?

Kirsty Wigglesworth/Associated Press

We're going to have to wait the best part of a year for the answers, but if the outcome is anything like what we've witnessed in recent times, it must surely be curtains on his Chelsea career.

How long can Mourinho continue to put his faith in a player who routinely disappoints?

Garry Hayes is Bleacher Report's lead Chelsea correspondent. All quotes were obtained firsthand unless otherwise noted. Follow him on Twitter @garryhayes