(C)GettyImagesRitabrata BanerjeeMatthijs de Ligt slammed for being 'lightweight' as Man Utd's latest signing questioned by ex-Liverpool boss Graeme SounessManchester UnitedM. de LigtLiverpoolPremier LeagueFormer Liverpool and Rangers manager Graeme Souness has questioned Manchester United's decision to sign 'lightweight' Matthijs de Ligt.Article continues belowArticle continues belowArticle continues belowArticle continues belowSouness raises questions over De Ligt's abilityNot the solution to Man Utd's problemsJoined the Red Devils from Bayern Munich on Tuesday