He told the club's official website: "I think Arsenal has done a good job [in the transfer window] because now we have five or six new players who have a very good level.
"I'm happy with the club and Alexis, Ospina, Calum, we have a lot of hopes for them so I'm happy with the team.
"We have signed four or five new players so maybe we need a little bit more time for the players to feel better and their fitness can feel better. I think in the next weeks the team will play better."
Arsenal host Manchester City on Saturday.