The transfer was met with an unsurprisingly positive uproar, per the Manchester Evening News, from the United fan base—who have seen the team that ran away with the title last year slump to a measly seventh place in this year's campaign.
In his first game for the club Mata impressed, with some crisp passing moves aiding to carve out several chances for his new team.
Both goals were influenced by the Spaniard and one would have to assume that as a player with a wealth of Premier League experience under his belt he will (much in the same vein as Robin van Persie) instantly adapt to life in Manchester.
All in all, despite the naysayers protesting that this huge sum of money being quickly splashed on a want-away Chelsea player was a "panic buy", Mata's arrival at the club is the best thing that has happened since securing the league title at home to Aston Villa last season.
However, while it would be hard to argue that this move has much of a downside, the suggestion could very easily be made that this fantastic acquisition and the excellent buzz it has as a result produced around Old Trafford somewhat masks the frailties that still remain in the Red Devils' dressing room.
At the mid-point of the window, before the arrival of Mata, the club had been linked strongly with the Bayern Munich defender Dante, per Sky Sports.
In the midst of the recent jubilation attentions seem to have worryingly turned away from any indication that a defender will be bought in this window.
While a lot of the core problems that the club have suffered recently have admittedly been a result of a poor midfield, it would be naive to completely excuse the defensive unit for some of the horrendous performances they have put in this year.
There is a reason that most United fans consider David de Gea to be one of their players of the year, after all. If de Gea had a slightly more solid and (crucially) consistent defence in front of him, the Spaniard would probably have considerably less work to do.
Before any fans start to flip their lids—I'm not suggesting that the young contingent of United defenders currently at the club are completely devoid of any talent.
Certainly players like Phil Jones, Chris Smalling and Rafael all show real promise and in time will mature into more regular first-teamers—in the case of Rafael this has already happened.
However, the back four—especially the centre of that defence (an area that in his autobiography Sir Alex says is what he built his teams around)—just aren't good enough right now to compete with most of their rivals.
Dante would have been a perfect short-term fix in the central area as players like Jones and Smalling garnered the extra year or two's experience to develop into seasoned, mature players.
The Bayern and Brazil man is no spring chicken. Aged 30, it's very true that his presence would have been a relatively short-lived one as he acted as more of a bridge between generations than starting one of his own.
With Nemanja Vidic and Rio Ferdinand approaching the end of their careers at the top of the game and Jones and Smalling, sadly for United, still not quite up to scratch, bringing in a player as experienced as Dante for a couple of seasons would have been perfect for the club.
As it is, all news of a potential swap seems to have completely blown over.
Is the current Manchester United defence good enough to win the league next year?
In the summer this is an area that David Moyes simply has to take into account if he wants his United side to challenge for the title in the 2014-15 season.
It's rare that a side's attack can carry a weak defence—not unheard of, but rare.
No matter how solid the team is going forward come the start of next year, if that central defensive area hasn't been improved on, then the side will struggle to challenge for the title once again.
It appears to be too late this window, however, and as such the team may well find themselves remaining outside the top four as a result.
For the fans' sake, let's hope that Mata, van Persie and Wayne Rooney's collective efforts are enough to drag them into the Champions League places once again.