Just had a break in the action so the grounds crew could pound the mound. Apparently John Lackey didn't like something about the uneven surface upon which his stride foot was landing.

Baseball players love to kick, dig, and otherwise mess up the playing surface at every opportunity, whether it's to dig their back foot in at the plate, get comfortable on the mound or play tic-tac-toe in the infield dirt during a game (a la Psycho Steve Lyons).

When you think about it, it makes you appreciate the patience and understanding of baseball grounds crews, who work very hard every day to get everything perfectly neat and level, only to see it systematically destroyed.