Sure. Arsenal bought players and spent a lot of money, but they are still finding it difficult to get what they want at the end of the season; however, to me this is not really from the players. I think the coach is the one who plans how these players will play their match, so for this he should be the one to plan what will suit these players and get what they want.
Just like you, a very passionate Arsenal fan I know did tell me that he's taken his time to study the club's performance in the last three seasons and have come to conclusion that Arsenal's problem isn't about the players but the manager. The truth is Arsenal is currently better than how they were when Mikel Arteta was appointed as the club manager but the Spanish manager really needs to step up his game and improve the team from being a regular title pretenders to a title winners. I believe he has the managerial abilities to achieve that if he really works to achieve it