#1 He doesn't want to be there, angling for Spain return
This is football's worst kept secret and has been for twelve months or so now - various media reports claimed he missed Barcelona, the competitiveness of Spain, the fierce derbies and opposition last summer.
In hindsight, you look back and ask whether he should have left in the first place? Probably not. He was comfortable at Barca and treated as a star, as part of the deadly MSN trio alongside Lionel Messi and Luis Suarez.
Instead though, he wanted to be his own man and not under Messi's shadow. Look how that's going for him! Now, he's suffering the same fate but instead alongside a younger, more marketable World Cup winner in Mbappe - who is also seven years younger.
Ultimately, what has he got to show for such a brave move? Some league title medals in a competition where rivals are completely inferior? That's not good enough for someone who has been underwhelming when it mattered most and will his fortunes change anytime soon? Doubtful at best.
It's a classic case of being careful what you wish for: he's his own man now and unhappy, but no player is bigger than the club. PSG know that and can still command a respectable fee for him, even if they'd be taking a loss on the £200m investment they boldly made.
"I want to build a new dream and achieve a new challenge with my teammates and family. I'm very happy to be another Brazilian to play for a great club in a great country. I heard people criticise Ligue 1, I have spoken to players about it, there are no easy games here. It is a big challenge for us to win the league again - we have great potential to be the world's greatest club.
I want to write history at PSG, there are new challenges and our biggest is the Champions League, but we want all the trophies. If I was following the money, I would be somewhere else in other countries. I'm glad PSG believe in me." Neymar during his PSG unveiling two years ago
The tide has shifted and he's wasting his peak years right now, having clearly not done his due diligence. Ultimately, it was exciting to begin with but the novelty quickly wore off and PSG found out the hard way. He's a flawed star and given their ambitions, one they cannot afford to carry.
Not committed to the club, he doesn't care enough and it shows - so why should they keep him? Instead, they need to invest smartly and rebuild by signing a world-class centre-back, midfielder in the Blaise Matuidi mould like Tanguy Ndombele and replace him with a quality attacker while return stronger for the experience in 19/20 and beyond.