Barring two reasonably good seasons, Nani has been largely frustrating - many would say infuriating - since arriving at Manchester United from Sporting Lisbon in 2007.

Not quite as frustrating as Anderson, who joined the Red Devils at the same time, admittedly - but so inconsistent that few United supporters would have shed a tear had he been sold in the summer.

However, instead of saying their goodbyes - a few would have personally driven him to the airport - fans of the Premier League champions were stunned by the news that the Portuguese winger had been handed an improved five-year contract in September.

Despite enduring his worst season since arriving at Old Trafford, Nani's wages were reportedly increased from £90,000 to £95,000 per week, while the prospect of the winger being handed a testimonial one day now looms large.

Of course, it's not difficult to understand why David Moyes acted quickly to tie Nani down to a long-term deal.

He's always produced the odd flash of brilliance, while his re-sale value is higher than many of his teammates'.

But it's been the same old story with Nani for years now: the rare brilliant game interspersed by periods of completely average displays.

He's never managed to score 10 Premier League goals in a single season before, while he tends to go missing in the most important matches - with the exception of games against Arsenal, who tend to see the best of Nani.

Instead of another five years of inconsistent dross from one of their highest-paid players, United could have cashed in and brought in a younger, more exciting talent.

The Red Devils could have recouped at least £15m for the 27-year-old - or even made a slight profit on the Portugal international - while plenty of wealthier overseas clubs would have taken him off their hands, so United shouldn't have feared the possibility of strengthening a rival club.

Nani has featured in just four matches so far this season - and Moyes really needed to ask himself the question: 'Does this player make my first-choice XI?' before handing him such a lucrative contract.

With the likes of Shinji Kagawa, Ashley Young, Adnan Januzaj and Antonio Valencia all vying for places on the flanks, Nani will get games - providing he's on top of his game.

But, sadly, an in-form Nani is an all too rare sight - and he will inevitably end up costing Manchester United a fortune over the next five years.

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