Firstly, and most importantly, it should be addressed whether Jose Mourinho would even allow Juan Mata to leave for Manchester United in the January window.
I mean, it would be a bit of a concern to United fans if he did. Under normal circumstances, the idea of Chelsea's manager allowing one of his players to move to a Premier League rival at any time—let alone halfway through a season—would be extremely surprising.
To do so would be to imply that Mourinho no longer considers United a threat (at least this season anyway), and even by his standards that would be a pretty hefty mind game. I mean, at the end of the last window he wouldn't even let Arsenal have Demba Ba on loan.
On the whole, moving between Old Trafford and Stamford Bridge is not exactly commonplace either. Just four players have played for both in the Premier League era.
Mark Hughes, Juan Sebastian Veron and Mark Bosnich all moved directly from United to Chelsea, and Paul Parker did the same via a few smaller clubs. Interestingly, none have ever gone the other way. Not really relevant in the slightest, but still interesting all the same.
January is not normally a time when United panic. No real significant business has been done in this window since Patrice Evra and Nemanja Vidic arrived in 2006. And even then, neither immediately established themselves as first-team players.
But this has been no ordinary season for the club, and Sunday's conclusive 3-1 defeat at the hands of Chelsea will have proved to everyone—if there was even a glimmer of doubt beforehand—just what a mighty gap currently is between them and the top sides.
Chelsea were never at their best, but victory was pretty much assured from the moment they went a goal ahead. They even did it without Mata, who remained on the bench throughout. Strength in depth certainly exists at Stamford Bridge.
Moyes needs to buy, and if there is even the smallest indication that the Spaniard may be available, he should do everything in his power to secure his signature.
But in the unlikely circumstance that the move did come to fruition, the other question exists over whether Mata would even fit in United's framework. Gary Neville, the ex-United player and current leading pundit in England, is sceptical. He said to Sky Sports:
Does he fit with what I would call the typical philosophy of Manchester United? I would say no.
The first question, I think, is where are you going to play? Wayne Rooney and Robin van Persie are up top if they are fit so where are you going to play him? Are you going to play him off the left or off the right?
We've seen Kagawa play off the left, we saw Kleberson play at times off the left, we've seen Veron at Manchester United move to the left because you can't play central midfield.
Maybe they have to change the philosophy and maybe that's what David Moyes is thinking. Maybe he wants to play narrow wide players and maybe a three in midfield.
You can understand where Neville is coming from. When you say "the Manchester United way," everyone sort of knows what that is—a combination of width, pace and crossing.
But what good is a philosophy when the players you have are simply not good enough to fulfil it?
Ashley Young, Antonio Valencia and Nani are all names that have begun to make United fans shudder to varying degrees.
Adnan Januzaj is a promising talent who has already become far too important, and I don't think anyone really knows what's going on with Wilfried Zaha.
So what, then, is the point of maintaining a philosophy of playing with width, if you don't have the wingers to play the system?
Even Sir Alex Ferguson, the ultimate dictator of Manchester United's overriding philosophy, abandoned his underperforming wide players for large chunks of last season. Perhaps it is time for Moyes to do the same, especially if Mata can be lured in.
Away from discussions of philosophy, Neville also highlighted the problem posed by Shinji Kagawa.
Does Moyes need another creative attacking midfielder who may struggle to adapt to the side when they already have one?
The Japanese midfielder was one of the finest attacking midfielders/No. 10s in Europe at his former club, Borussia Dortmund, but he has yet to reach those heights in 18 months at Old Trafford.
He has been in and out of the side and played in a number of different positions. Then, whenever he has been given the chance in his favoured central role, it is hard to suggest he has ever really done enough to nail down the place long-term.
Mata, though, is a better player than Kagawa. Simple as that. He adapted to the rigours of the Premier League almost immediately upon arrival and was by far Chelsea's outstanding player in his first two seasons at the club.
Kagawa generally looks pretty uncomfortable anywhere other than in a central role, but Mata has proven himself to be incredibly adaptable during his time at Chelsea.
A first, he excelled where others struggled under Andre Villas-Boas and his 4-3-3 formation. Then, he proved himself pivotal in Roberto Di Matteo's extremely defensive Champions League-winning side and again in his far more flexible attack-minded 4-2-3-1 formation alongside Oscar and Eden Hazard.
Then, Rafa Benitez came along and made Chelsea far more structured and organised, but Mata still flourished in a No. 10 role. He is no one-trick pony, which has made Mourinho's dislike of him this season all the more surprising (a topic for another day, mind).
Neville also argued that:
They would have to change to accommodate Juan Mata in the way they normally play. They normally play with wide players. Sometimes they tuck in, but generally they have wide players and the thing for me is where is he going to play?
Yes, they would have to change slightly to accommodate him. But would that be such a bad thing? It's not like this current Manchester United system is doing particularly well at the moment.
A bit of freshness and variety wouldn't exactly hurt.