The Argentine’s arrival was particularly surprising given that he had recently impressed at the World Cup as a left-back, but he has featured predominantly in the centre of Louis van Gaal’s defence this season, improving on his form there for former club Sporting Lisbon.
Mangala’s move was far less surprising, such was his reputation in the game and the need for City to strengthen at the back.
But with both players now well and truly settled in England, how do their Premier League performances compare?
As you can see, there are five key areas where the United defender is currently outshining the French international.
Rojo averages more tackles per league appearance, wins considerably more interceptions, commits less fouls, makes more effective clearances and wins more duels on average per game.
|Tackles per game||Interceptions won per game||Fouls per game||Effective clearances per game||Duels won per game||Aerials won per game||Appearances|
When it comes to aerial battles - an area one would assume the City player would excel in - the duo are neck-and-neck, averaging 2.79 successes every game.
Given that both the United and the City players have both turned out 14 times in the league this season the comparison is a fair one, and it will be interesting to see how the two develop in the years to come.
Rojo may have been a surprise choice to come in when United had recently seen Nemanja Vidic and Rio Ferdinand leave the club, but he has justified his price-tag and looks like a very canny investment.
Mangala has also settled well despite some erratic performances in his early weeks at the club, but for now it is Rojo who is likely to be more pleased with his contribution to his new club's back-line; at least in terms of the statistics above.