For being the worst player in the majors. And it's not even close. His VORP (-26.3) is far worse than the next worst player in the bigs, Craig Monroe (-15.0). Punto is hitting a robust .199/.288/.256 in 467 PA for the Twins. He's threatening to become the first player since Rob Deer (.179 in 1991) to hit less than .200 in a season of 500 or more PA. And isn't that just as exciting as a player chasing .400? It's always nice to see a guy really, truly flirt with the Mendoza Line.
Of course to have the lowest VORP in the league, you need to accrue some significant playing time. So Punto isn't really the worst player in the majors right now. At least I'm not sure that he is. There are untold dozens of players who could have been just as bad if given enough plate appearances. But isn't that the important part? Not everyone can hold a regular job at 3B with a .256 slugging percentage.
Punto has been a good enough defender to get his WARP to exactly 0.0 on the season, making him the definition (or at least BP's definition) of a replacement level player. So he's only the worst hitter in the league. But that's not half bad.