Mikel Arteta needs his big players to step up in the vital moments during one of the most important periods in Arsenal’s recent history. The problem is that two of them are out for the season. The Gunners are aiming to reach the Champions League for the first time in five years, in what would be a milestone moment for their progression and improvement under their young Spanish head coach. But since Kieran Tierney picked up a serious knee injury at the start of the month, the Gunners have lost three games out of three. Thomas Partey picked up a thigh problem in the first of those games – a 3-0 defeat at Crystal Palace – in a further blow to the Gunners’ top-four hopes. The statistics show that Arsenal are a much more cohesive unit with both Tierney and Partey in their squad – and that their absence is detrimental to Arteta’s game plan. So what makes Partey and Tierney so crucial to Arsenal – and how does the Gunners manager get around this problem? Defensive struggles Many p...