With Nemanja Vidic having sealed a switch to Inter Milan this summer and Rio Ferdinand's current contract also expiring in June, it's clear that Manchester United have big changes to make at the back. The likes of Phil Jones and Chris Smalling were signed to step up when the time came for their senior team-mates to move on but David Moyes certainly needs to bolster his backline.

It's no surprise then that a number of players have been mooted with a move to Old Trafford, with WhoScored.com taking the chance to compare some of those touted as replacements for the old guard. To do so we've looked at the stats of each from this season and last, in the matches that the players chosen have started at centre-back.

Thomas Vermaelen

Arsenal's Thomas Vermaelen was entrusted with the captain's armband at the Emirates following the departure of Cesc Fabregas but his form and playing time has diminished since. Now firmly the third choice under Arsene Wenger it seems the Belgian is surplus to requirements and could be made available. With just three league starts under his belt this season, Vermaelen has made a total of 25 appearances at centre-back since the beginning of the previous campaign.

His average rating in those appearances is a modest 6.94, with a pass completion rate of 86.7% and an average of 2.8 aerial duels won per game. Averages of 1.6 tackles and 1.8 interceptions per game are respectable but having previously become a fan favourite for his goal threat from the back the Arsenal man hasn't netted in the league in the past two seasons.

Eliaquim Mangala

Porto's 23-year old centre-back is tipped to become one of the best in Europe and cement his place in France's national side. He did his chances no harm with a solid showing alongside Raphael Varane against the Netherlands last week, winning seven aerial duels while completing 12 clearances and 95% of his passes. The week before his brace ensured Porto's progression in the Europa League, so his stock is certainly rising.

With Liga Sagres stats unavailable we're looking at Mangala's 11 starts at centre-back in Europe over the past two seasons, so the quality of opposition will have impacted on a decent rating of 7.00 in those matches from WhoScored.com. His averages of 1.4 tackles and 1.8 interceptions per game, along with 2.3 aerial duels won per match are similar to those of Vermaelen, but with two goals and one assist to his name he holds a threat at the opposite end of the pitch too.

Davide Astori

Having come through the ranks at AC Milan, 27-year old Astori has become a key player in his five seasons with current club Cagliari, earning international honours in the process. A call-up to Cesare Prandelli's World Cup squad is certainly on the cards for a defender who boasts impressive defensive stats across the board.

Since the beginning of last season the Italian has started 55 matches at centre-back in Serie A, with notable averages in terms of interceptions (2.4) and clearances (8.8) per game. If Astori has one weakness, as shown by his WhoScored characteristics, it is his concentration, having made more errors that have led to goals than any other outfielder in Serie A (four) in that time. Nevertheless, the Cagliari man certainly has a number of attributes that would cover for the loss of Vidic, with an average rating of 7.14 over the last two seasons.

Mehdi Benatia

It's a case of saving the best for last here, with Roma's Mehdi Benatia having firmly established himself as one of the strongest centre-backs in Europe this season. He confirmed interest from a number of parties last summer but said that after giving Roma his word he would not back out of a move to the Stadio Olimpico. His availability now is uncertain, and with Roma looking more than likely to qualify for the Champions League and United looking distinctly unlikely to match that feat, whether the Moroccan would consider any such move is equally unclear.

If Benatia were open to a move to Manchester the stats suggest he'd be an excellent acquisition. The 26-year old's averages of 2.7 tackles and 3.1 interceptions per game over 45 league starts at centre-back in the last two seasons are very impressive, while he's netted a noteworthy seven times in that period. With United's current quartet having notched just four goals in 93 league starts between them since the start of the previous campaign, Benatia's goal threat is clearly something the champions have lacked. A WhoScored.com rating of 7.52 in the last two seasons is evidence enough that Benatia would be worth the high sums that any transfer would likely command.

All statistics courtesy of WhoScored.com, where you can find yet more stats, including live in-game data and unique player and team ratings