After Jose Martinez's walk-off hit, the Cardinals showered ... a reporter
Usually after a player ends the game with a walk-off hit, he does a postgame television interview. It is customary for his teammates to interrupt these interviews to dump gallons of ice cold Gatorade on the player as a way to celebrate his contributions to the win.
If the cooler had been dumped on Martinez, we would have noted that it was because his teammates were expressing appreciation for his walk-off single. We can only assume that the Cardinals are congratulating this reporter on a job well done in this instance as well.