With Chelsea's reported £20 million capture of Filipe Luis having been confirmed, there have been inevitable questions about the sensibility of Manchester United paying £30 million to bring in Luke Shaw from Southampton.Even devoid of the context of Luis's signing, the fee paid for the relatively untested Shaw seemed a bit steep. Considering Chelsea's new acquisition won La Liga and reached the Champions League final last year, it seems even stranger.Shaw has emerged as one of the most highly-rated defensive prospects in the Premier League after a breakthrough season with Southampton, with Man Utd having maintained an interest in his signature throughout the managerial changes of last year. That said, £30 million seems an incredible fee for a player with only one proper season of Premier League football under his belt, during which his side finished mid-table.Luis, on the other hand, has been a key part of Diego Simeone's revolution at Atletico. Last year they shattered the hegemony of their city rivals Real Madrid, and Barcelona at the top of La Liga, winning the championship for the first time in 15 years.He was impressive to the extent that former Liverpool hero Jamie Carragher wrote, regarding Luis's omission from Brazil's national side for the World Cup, “I’m still astonished that Atletico Madrid’s Filipe Luis is not in the squad, never mind the team, as I didn’t see a better left back in Europe last season — or in this competition to date."On paper, it seems as though Chelsea have got the vastly better deal, but on a deeper level, Shaw might be the more sensible buy. Luis is 28-years-old, and given the physical demands placed on full-backs in the modern game, Chelsea will almost certainly have to replace him in a few years. Shaw, on the other hand, is only 19, and should he fulfill his potential, could ply his trade on the top level of European football for years to come. Chelsea's combined outlay for full-backs over the next few years could end up vastly outstripping United's.Though, on a basic level, it may seem that Luis has outperformed Shaw when their attacking statistics over the course of last season are compared. Luis managed more assists for his teammates and was very slightly more accurate with his passing.However, despite Luis's better assist record last season, doubling Shaw per minute played, the situation is not as it seems. The Southampton defender was far better at the simple action of chance creation and played more key passes per 90 minutes played, too.Given the disparity between Southampton's position at the end of last season and that of Atletico, it's reasonable to suggest that a player in Shaw's boots might find fewer of his chances being converted, given the relative quality of the players in attacking positions. No one has compared Rickie Lambert's switch to Liverpool to Diego Costa's move to Chelsea as being examples of players of the same standard.Therefore, it might be that Man Utd have got the better end of the deal, in the long-term. Given the attacking onus placed on full-backs these days, Shaw might end being the better buy.Furthermore, Chelsea will likely have to replace Luis in a few years, whereas Shaw can be a long-term addition to Man Utd's squad, assuming he fulfils the potential he clearly has.(uk.eurosport.yahoo.com)Bakudaily.az