What am I inventing?
As I said, it's not my opinion but the opinion of other people who follow portuguese football.
I don't have the insight that you have, I'm an outsider looking in when it comes to the portuguese League. But a Quick look at his games this season shows he's got 1 goal in five games against Porto and Benfica. Schalke aren't a big team, they concede as many goals as they score. All the games in which he's scored and assisted have been in games against low quality teams that someone who doesn't follow portuguese football probably never even Heard of.
As I said in my initial reply, I agree that I'd rather have him back than give him away but I don't think he can reach the level he once held and this season certainly hasn't convinced me otherwise as the only difference between this one and the preceding two seasons are that he's managed to stay relatively injury free and generally faced opposition of inferior quality. The numbers he's put up pretty much matches the likes of his competitors in the League, i.e Brahimi (7/6), Quaresma (6/6) and Gaitan according to transfermarkt got 4 goals and 15 assists this year not 4 and 7 as you said in your earlier post. Those numbers, in that competition, just don't impress me much.
I'll concede that I'm often pushed into extremism and unreason when it comes to Nani because of how our own fans every year in his abscense (due to injury or other) big him up as the messiah to our offensive troubles only to crash down on him when he can't perform to those expectations. Maybe I'm just trying to manage, or balance expectations. I'm on very thin ice here indeed.
Ok, so it´s people who follow portuguese football. People that seem to be as clueless as you are if they think Nani is bellow Gaitán or Brahimi. If i take the gloryhunter path and neglect our domestic football (just because you don´t know the teams, doesn´t mean they don´t have quality or aren´t hard to play at their stadium, i mean Braga beat Arsenal in the Champions League some years ago), if we compare Gaitán or Brahimi´s performances in the biggest competition (the Champions League), they haven´t came close to replicating the level Nani has achieved. Nani this year in a weaker team (comparing to United) put up better performances than Gaitán ever produced in europe. United fans have every right to have an opinion and not wanting Nani back but to comparing him to Gaitán is laughable. There´s a reason why he is still stuck at Benfica at 27 years of age. It´s because he isn´t good enough to warrant a top club move. Something that Nani has achieved and justified for a couple of years.
Again i´ll educate you about Nani´s performance in the big games. Just because he didn´t score or assist doesn´t mean he wasn´t "productive". This year´s the portuguese big games, have been very close, with few goals and very balanced affairs. Nani has been very good in 90% of the big games. And he plays in a supposedly "inferior" team with 1/3 of the budget compared to Porto and Benfica. He certainly been better than Gaitán and Brahimi in the big games. The only player that outshinned him once was Tello for Porto in the Dragon stadium game, where he was amazing. But for example in the Portuguese Cup Porto game away, Nani was MoM with an amazing goal and assist. Biggest criticism about Nani from Sporting fans was some of his perfomances against the smaller teams, where he wasn´t as motivated and couldn´t be arsed. In the big game, he was always a top performer and some lack of results weren´t due to his "production" but rather having a very limitated striker up front and a very frail defence.
About Gaitán numbers i took them from a Benfica blog, i guess they weren´t uptdated. But the numbers for the Champions League were and prove his poor campaign and lack of influence in an underachieving Benfica team. Nani on the other hand was the bright spot of our campaign, the main driving force in an almost sucessful campaign (we missed the next stage because of a referee mistake in Germany where the ref gave a penalty to Schalke for a "handball" that hit our defenders head). The same Schalke that put up a big fight against Real Madrid. So they aren´t a big team but they were (this year) in Europe a decent side. Certainly a side with much more resources and financial power compared to us.
I already gave my opinion about Nani. With Memphis and Di Maria (if you keep him) in the wings, i think you should sell Nani. He´s already 28 years of age and wants to play first team football in order to keep his Portugal national team spot. For those reasons, i think that staying at United will damage his chances of replicating a very positive football year that he achieved at Sporting. If he is willing to stay and fight for spot in a very long season that United will have next year, i think he will have some chances because let´s face it, it´s not like your other wing choices had an amazing year (this if you don´t buy more wingers). He could be useful but of course knowing Nani´s expectations, i would sell him since he appears to have market interest in Spain, Italy and even in England.