There are hundreds of details that you have to pay attention to as a ballplayer. You need to focus at the plate, determining the difference between a fastball and a slider in absolute milliseconds. Out in the field, you need to be prepared for the ball to bounce and hop every which way. And, as the Marlins' Jesús Aguilar proved at Thursday's Mets home opener, you've always got to be ready for a clever pickpocket.

Yes, like the early days of city living, when child pickpockets were something you had to look out for (seriously! There's an academic article on that if you want to read), players at first base now have to watch out for this kind of thing, too.

Who knows what Aguilar grabbed, too. Perhaps it was the Mets' defensive alignment cards, so now the Marlins will know all of New York's defensive secrets. Or perhaps it's simply a receipt from CVS -- though we'd imagine that would be much larger. Heck, maybe it's a pocket-sized diary with all of Smith's deepest secrets hidden inside.

This appears to be a growing trend around the league, too. At the end of Spring Training, Willians Astudillo was found looking through Xander Bogaerts' pockets, only to come up empty. It's only a matter of time before signs telling players to watch out for their belongings are posted all over the clubhouse.