Laurence Griffiths/Getty Images

Nani has signed for Fenerbahce and on his Instagram page he shared an emotional goodbye to his Manchester United career. 

Captioning his photographs of trophy presentations and a cuddle with Sir Alex Ferguson, he wrote:

"I leave Manchester with many titles and many memories, I want to thank all the people who helped me on this journey and wish you all the luck and success! Thanks to all my colleagues, to all staff and management structure, thank you Sir Alex Ferguson!"

Nani's United career was, of course, a distinctly hit-and-miss affair. Newton's Third Law of Motion tells us that for every action there is an equal and opposite reaction."Nani's Law" would tells us that for every moment of brilliance there was a misplaced pass or an infuriatingly poor shot. 

Let's take a look at the best and worst of the back-flipping, outrageous dribbling, goal-assisting, headache-inducing enigma that was his United career. 

Honourable mentions should also go to a couple of stellar performances against Arsenal.

Newly-arrived Nani scored an absolute screamer in August 2007, announcing himself as a signing with huge potential. 

The goal was a brilliant bit of individual play where he carved out space for himself and smashed the ball past the helpless 'keeper. The celebration was euphoric and dramatic—all back-flips and somersaults. 

It was hard not to get giddy about his prospects at that point, especially given the inevitable comparisons with Cristiano Ronaldo.

Jon Super/Associated Press

This was Nani at his most wasteful, and least effective. 

On the back of a second fine season in 2011/12, hope remained high for Nani's effectiveness as United looked to retain their title. He got off to a dreadful start, and in many ways, this game was the beginning of the long downfall of his United career.

He was in Sir Alex's starting XI that day, but by the time he had been replaced by Ashley Young he had managed an old-fashioned stinker. According to Squawka.com, he had one shot, which was off target. He had completed 78 percent of his passes, but not managed to create a single chance as almost all of his passing in and around the box was wayward.

He had attempted eight crosses, none of which had found their man. His one take-on attempt failed.

It was easy to write off the poor performance as opening-day ring rust, but the rest of that season suggested something more serious was wrong...

Alex Livesey/Getty Images

A few years earlier, and the picture looked very different. 

The triumvirate of Owen Hargreaves, Anderson and Nani were all signed in the same summer. Ultimately, each one must carry regrets about their United careers, but they got off to a remarkably good start. 

By the end of his first season, having scored three goals and provided six assists, Nani was a Premier League and European champion. He did not start in the final but made an enormous contribution after coming on in the 101st minute. 

By the time he stepped up to take his penalty in the fateful finale, he had to score to keep United in it. Which he managed to do. 

Under immense pressure, having watched Ronaldo miss one, Nani stepped up and ensured that triumph was still an option. 

Jon Super/Associated Press

The aforementioned Everton game proved to be a foreshadowing. 2012/13 was the season in which Nani's United career dropped off a metaphorical cliff. 

One of the key reasons for this was the number of injuries he suffered. He had enjoyed reasonably good fortune in injury terms during his first few seasons at the club. However, from November 2012 to February 2014 he was unavailable for selection for 37 games, per Transfermarkt.co.uk. He missed almost six months of action in that 15-month spell.

During that time he saw his team-mates winning Sir Alex's final league title, and David Moyes arrive. He made just 14 league starts across those two seasons. In the Moyes season he neither scored nor assisted a goal in the league. 

The long, slow goodbye, as repeated injuries and absence from the first-team picture dented his apparently fragile confidence, was the certainly the lowest low of his time at Old Trafford.

Michael Regan/Getty Images

It seems only fitting, though, to leave on a high. Nani's peers clearly rated him as in 2011, they voted him Players' Player of the Season. 

It was easy to see why. He was superb in 2010/11, scoring nine goals and racking up 14 assists in the league. He was devastating on United's right wing, averaging 2.5 dribbles and 2.4 key passes per league game, per WhoScored.com.

During that period he was so much fun to watch. Unpredictable and explosive, when what he tried came off, it was very good news for United. Of course, even at his best his unpredictability could be infuriating, but the good far outweighed the bad that season. 

He leaves United with four Premier League titles to his name, and he was an integral part of three of those campaigns. He may leave with some regrets, but there is an awful lot to celebrate about Luís Carlos Almeida da Cunha's United career.