From the official site:

Yankees first baseman Doug Mientkiewicz will be placed on the 15-day disabled list after being involved in a violent collision at Fenway Park on Saturday. ...

... Tests at Massachusetts General Hospital revealed a mild concussion, cervical sprain and a fractured scaphoid bone in Mientkiewicz's right wrist.

Brett Nycz says that we'll be without him for 9-12 weeks.