When Nastasic made his breakthrough in the 2012/13 season it seemed that his partnership with Vincent Kompany in the centre of the Citizens' defence would be one that City would build their defence, and in part their team, around.
It has all gone downhill from there for the Serbian, with the 21 year-old missing most of last season due to injury and only featuring once for City this term – in the season-opening Community Shield.
So prolonged was his absence that Manuel Pellegrini stopped making mention of him when discussing those missing from City's once struggling defence.
Nastasic is not alone in struggling on the periphery at one of the league's frontrunners and we look at three other young guns who should consider a swift exit from their respective clubs…
Joel Campbell (Arsenal)
Six months ago many Arsenal fans would have been eagerly anticipating seeing Campbell in action after his strong showing at the World Cup for Costa Rican, with all signs suggesting that the striker has what it takes to succeed at the highest level.
However, it remains to be seen if he does, as Arsene Wenger has refused to give him any sort of run in the team, with one start and a few brief appearances off the bench the only opportunities that have come Campbell’s way.
Recent reports suggest that Campbell is set to join Benfica, a team he was linked to in the off-season, and the move can’t come soon enough for the 22-year-old; he can still ride on his performances in the World Cup now, but in six months time the memory of failing at Arsenal will be much greater than succeeding with Costa Rica.
Mohamed Salah (Chelsea)
Salah’s problem appears to be that Jose Mourinho appreciates his talents – but not quite enough for him to play regularly.
While the Blues have a plethora of youngsters out on loan, the 22-year-old Salah has remained at Stamford Bridge in order to make a handful of appearances.
Of the 16 players Chelsea have allowed to leave on loan, eight count themselves as attacking midfielder or wingers; it's certainly a position Jose Mourinho is well stocked in. With that in mind, it's perhaps an illustration of Salah's skill that he is still in west London.
However, while Salah has youth, and great talent, on his side, he risks losing some of his shine if he strays too far out of the limelight.
Scott Sinclair (Manchester City)
It’s fair to say that Sinclair’s big-money move to Manchester City has not gone according to plan. The winger has featured just 18 times for the Citizens since making the move to Eastlands.
A loan move to West Brom last season threatened to kick start his faltering career, but Sinclair’s belief that he can make it at City could be damaging his career.
The former Swansea star wouldn’t be the first player to have failed to make it at one of the league’s big spending top dogs, and cutting his losses now may be a good move.