It could be argued that the role of defenders has evolved more than any other position over the past decade. Full-backs are often being inverted into midfield and sometimes even employed as No 10's, while the role of the centre-half at the top level has also been somewhat revolutionised. Pace has become a paramount factor, with teams frequently operating with a very high line. More recently, top clubs like Manchester City and Arsenal are even playing orthodox centre-backs at full-back to solidify their defence and provide balance. While the starlight and most expensive transfer fees still often go to forward players, clubs have begun to invest heavily in their back line as well as attackers.