The sterling signing has addressed more than one weakness however. He has added pace which was required. He provides more assistance to the left back which was an area often exposed last season. You can see after two games how Kolarov seems a better player. He has allowed Silva to play central and control the game more. He has lowered the average age. He has improved the homegrown quota. He has weakened another team in the league.
That's why were so keen on getting him and willing to pay the fee. One player can address more than one issue.