Tony La Russa watched about 130 games last season in his role as a special assistant to Commissioner Bud Selig. With the sharp eyes of a Hall of Fame manager, he paid close attention to plays that would need to be reviewed by video.

“You really don’t need a pocketful of challenges,” La Russa said by phone on Thursday, adding later, “It doesn’t come around all that often.”

Now we will learn if La Russa’s hunch is correct. Major League Baseball announced Thursday that its teams had unanimously approved the expanded use of replay for 2014, and that the players’ and umpires’ unions had also agreed. The plans have been modified since August, when they were first announced, and will add another vital element of strategy for managers.

When La Russa and Joe Torre met with the current managers at the winter meetings last month, they found some managers worried about adding another responsibility. Why burden them with the task of deciding which plays to challenge?