Pirates right-hander A.J. Burnett is one of baseball's very worst pitchers when it comes to holding on runners and preventing stolen bases. Opponents have gone an insane 103-for-117 (88-percent success rate) against him in stolen-base attempts since 2010, which is outrageous.
I guess he just decided to make everyone's life easier and intercepted the throw. Saves time and energy, plus it reduces the risk of the second-base umpire making a bad call. Burnett is just thinking of the people around him, really.
(h/t Getting Blanked)