The 27-year-old began training with his new club this week ahead of a potential debut against Manchester City at the weekend.
“Thomas is going to give us more versatility in our way of playing," Arteta said. “He can play in two or three different positions when we are able to change formations or game plans against opponents.
"He will give us something that at the moment we don't have in the team.
“We need a balance between the young players we have in breakthrough or development phases and others that are at the peak or twilight of their careers.
“Thomas is the right recruit for us in terms of age, his history and career, where he has been educated, the amount of experience he has and the quality that he has to adapt to our game."
Arteta is careful not to place too much pressure on the former Atletico Madrid man as he looks to settle into life in London.
“There is a lot of expectation, but we have to give players time to adapt," the Gunners' boss added.
“The Spanish league and the Premier League are completely different, the style of play of Atletico and ours have some big differences as well.
“What is unquestionable is the quality of the player and the level he has been playing in the last five or six years. That will be a big help.
"If he has the support of the coaching staff, players and fans that I can see, then obviously the adaptation will be quick."