O'Conner was DFA'd by the Rays on Monday, Marc Topkin of the Tampa Bay Times reports.
O'Conner missed nearly all of last season due to a strained back, and the 24-year-old, first-round pick (2010) is yet to progress past the Double-A level. Monday's designation removes O'Conner from the 40-man roster, freeing up a spot for the newly acquired Wilson Ramos.