Cubs beat writer Patrick Mooney of CSNChicago reports that Javier Baez has been placed on the AAA disabled list:
Cubs put top prospect Javier Baez on the disabled list: http://t.co/QHMNPD0YV6 
— Patrick Mooney (@CSNMooney) April 13, 2014 
It sounds like a sprain, which shouldn’t sideline Baez for more than a couple weeks.
The top prospect was off to a sluggish start this year with the Iowa Cubs, batting just .154 with a .637 OPS and 10 strikeouts in eight games played. Baseball Prospectus ranked Baez the No. 4 prospect in the game this winter and the 21-year-old should be up in the majors by the end of the 2014 season.
Source: Drew Silva (NBC Sports Hardball Talk)