Considering the mountain of official information that is out there to enlighten us, fans, it's starting to become embarrassing how there are still fans who think Emery 'signed' any players for Arsenal.
Even though this has been explained on several occasions, I'll break it down one more time.
Responsible for recruitment (post-Wenger) were/are:
Ivan Gazidis (Chief Executive - Gone)
Role disbanded following his departure.
Sven Mislintat (Head of Recruitment - Gone)
Role disbanded following his departure.
Raùl Sanllehi (Head of Football - Active)
Involved in transfer activities, contract negotiations and all things football. Only really answers to Stan/Josh.
Vinai Venkatesham (Managing Director - Active)
Raùl's right hand. Predominantly focuses on financials. Also involved in contract/transfer negotiations along with Huss Fahmy.
Edú Gaspar (Technical Director - Active)
Arsenal's very first TD. Oversees all technical aspects, from the first team, to the academy, to recruitment, whilst advocating and respecting the club's philosophy.
Francis Cigagao (Head of Scouting - Active)
Leads the team that's responsible for scouting activities and recruitment. Answers to Raùl and Edú.
Unlike Head Coaches, Managers combine their job of as coach with Technical Director or even Director of Football. AW was Arsenal's last Manager. He lost his managerial powers the season before his departure during a power struggle with Gazidis.
Unai Emery was signed as Arsenal's Head Coach and, thus, had no final say on recruitment. At most he could make a recommendation, with emphasis on
recommendation. The same currently applies to Mikel Arteta.
Arsenal have opted to share the responsibilities of a Manager between a group of people not only to share the workload, but also to prevent one individual from becoming too powerful, like was the case with AW.
All Managers are Head Coaches but no Head Coach is ever a Manager.