The Brazilian said that the £7.5m capture caught him off guard, but added that the Spaniard's experience will help his team compete on three fronts this season.
"With Mehdi Benatia I wasn't surprised," he told TZ. "But with Xabi Alonso it all happened incredibly fast and we knew nothing about it in advance.
"We are playing in three competitions and want to win all three, so we need a lot of players. I stand by my opinion - when players come with the quality of Xabi or Mehdi, it is always good.
"I've only trained with him a few times but in the game against Schalke you already saw that he is a great personality. Xabi has an incredible amount of experience and can help us right away."
Alonso made his Bayern debut in the 1-1 draw at Schalke 04 on August 30.