Arsenal paying price for summer transfer mistake as Edu eyes Kieran Tierney replacement

Arsenal may be paying the price for a potential mistake made in the summer transfer window when it came to letting Kieran Tierney leave on loan to Real Sociedad. The Scotland international moved from a key player for the Gunners to an outcast as Mikel Arteta tweaked his system last season.

The arrival of Oleksandr Zinchenko put more emphasis on an inverted full-back role, where the defender would be required to slot into midfield and add a stable base in possession. That doesn't quite match the skillset of Tierney, who has predominantly favoured overlapping on the flanks.

The signing of Jurrien Timber in the summer and his eventual place at left-back in pre-season appeared to point towards an exit for Tierney, which duly followed. The 26-year-old may have been missed though, with his loan deal potentially paying the price for Arsenal so far.

While hindsight is obviously a handy thing to have, there was some signs that a possible stay was required for the defender in the summer. The first was that Timber, his possible replacement, suffered his anterior cruciate ligament injury weeks before Tierney left, with the diagnosis confirmed roughly two weeks ahead of the exit.

That could have been enough time to stop the deal from happening and working with the squad at their disposal, but it wasn't the case. There were always going to be injury doubts over Oleksandr Zinchenko and Takehiro Tomiyasu, due to the pair often finding themselves on the sidelines with occasional problems.

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On top of that was the knowledge that Tomiyasu was likely