Why Oscar Is the Chelsea Player with Most to Prove in the Final Weeks of Season

Is there a more frustrating player at Chelsea than Oscar?

The Brazilian is capable of remarkable moments of brilliance, yet equally he disappears enough at times that there's an argument to suggest he doesn't warrant a place in Jose Mourinho's matchday squads, let alone his starting XI.

There's a trend.

Oscar starts the season in excellent form, but come the new year his performance level dips significantly.

From creating opportunities, finishing off attacking moves and implementing Mourinho's pressing game from the front, he's the opposite from January onwards.

We saw it in his first campaign, and last season was no different.

In 2012/13, the theory was that it was a symptom of him adjusting to English football; last year that his mind was elsewhere, notably on the approaching World Cup in his homeland.

So what about now? Is it fatigue or worse—a lack of substance in dealing with the expectation that surrounds Chelsea come the business end of the season?

They're valid questions, and whatever the answer, it's not exactly positive news for his club.

Indeed, whichever way the penny drops in that scenario, Mourinho has a problem on his hands.

It's up to Oscar to show his manager that he hasn't.

Clive Rose/Getty Images

If fatigue is playing a part in Oscar's traditional end-of-season slump, the club must address it. Does Mourinho rest him at times throughout the year or simply persevere, front-loading his games until the inevitable happens?

And if it's the latter, Oscar needs some serious psychological coaching to come to terms with the Chelsea pressure cooker.

We've seen plenty of times this season alone what happens to teams when the pressure is off. Take Schalke and their recent 4-3 Champions League victory over Real Madrid at the Bernabeu.

After their 2-0 first leg defeat at home, little was expected of Roberto Di Matteo's players. When they arrived in the Spanish capital, that gave them licence to play with freedom—after all, what was there to lose?

The shackles were off, and we saw the likes of Klaas-Jan Huntelaar finally live up to their billing on the big occasion.

Julian Finney/Getty Images

The same can be applied to Oscar.

Beginning the season, games mean little. Sure, there's always a requirement to win matches, but it's only in the latter stages that any pressure becomes tangible.

It's at the turn of the year when performances are significant. The matches are bigger, and trophies are on the line. And it's when Oscar disappears.

How long can Chelsea accept that?

The reason Mourinho's team suffered a premature Champions League exit was as much down to their own shortcomings as it was Paris Saint-Germain's determination to win that last-16 tie.

Too many of Chelsea's big names failed to show, and Oscar was among those who were most guilty.

Jamie McDonald/Getty Images

He made headlines, but for all the wrong reasons. We weren't left debating Oscar's ability, the topic of conversation instead was whether his amateur dramatics in Zlatan Ibrahimovic's dismissal at Stamford Bridge deserved an award representative of his name.

That's where the frustration sets in.

Why are we left to discuss Oscar in these terms when we know he is capable of so much more?

In the sense he doesn't show for a full campaign, Oscar's a part-time footballer. So much so, Mourinho seems reluctant to pick him post-Christmas as he doesn't know which player will turn up.

Before the season is out, he needs to show us it's otherwise. Should he not, where does that leave his Stamford Bridge future?

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