#4 Rob Holding solid at the back
Rob Holding was one of Wenger's last buys - well if analysed over the course of his long tenure. He signed in 2016, from Bolton Wanderers, and whilst little known at the time impressed greatly with a performance vs. Leicester City (who were then the reigning champions). He also won the FA Cup that season, with an impressive display vs. Chelsea.
He hadn't featured much in 17/18, in Wenger's last season of course, but then vs. Watford, he showed the qualities that made Wenger buy him.
With an ageing Koscielny and a somewhat erratic Mustafi, Holding has an opportunity to stake a case for regular playing time.
Credit must be given to Wenger for identifying him, but under the new Emery regime, he may receive additional guidance to become a top-class central defender.