The French star, 22, sealed a £5million move to The Emirates just 10 minutes before the transfer deadline.
And he admitted: "I needed to play and get more time on the pitch and I don't think it would be possible at Chelsea. That's the main reason why I left. At Chelsea, we had Michael Ballack, Frank Lampard, Claude Makelele and Michael Essien in midfield.
"I know it will be tough to make it at Arsenal as well.
"I have no guarantee from Arsene Wenger I will play all the time but I am sure that it will be OK.
"I know I will play big matches in the league and even in the Champions League."
And he added: "I knew for some time Mr Wenger was interested in me.
"He watched me with Chelsea and the France national team. They were my first choice and my first priority.