Emery always has been a very good manager, but he had a near-impossible job in taking over late-Wenger Arsenal. Front office was unsettled (multiple sporting directors in his 1.5 seasons), a dressing room with senior players who didn't buy-in and undermined him, and fanbase clearly upset at the malaise that had set into the club. Despite that, he had us on a ~ 10-match winning streak his first season, made the EL Final (which to this day I firmly believe we would have won had we faced a European side instead of a London Darby v Chelski in Baku), and brought Academy products Saka and ESR through to the first team. Nothing but respect for him, and I hope he leads Villa to a second place finish this year - behind us of course.
It took Arteta a few years to get the rot out of the club, fully backed by a stabilized front office of Josh and Edu, and KSE's funding once they acquired 100% ownership of the club.