Why, you ask from whatever rock you just climbed over? Well for starters, the dude went crazy and hit four home runs in a single game, which was apart of his nine home run, 18 RBIs and 10 runs scored seven-game stretch.
This award comes fresh off Hamilton winning the AL Player of the Month award in April. This, from the MLB release sort of put it all in perspective:
Texas Rangers outfielder Josh Hamilton, who became just the 16th player in Major League history to hit four homers in a game on Tuesday, has been named the American League Player of the Week for the period ending May 13th. This is Josh's second career weekly honor (last on 6/24/2010). The announcement was made earlier today on MLB Network . Hamilton turned in one of the greatest weeks of all-time, highlighted by Tuesday's performance, in which he went 5-for-5 at the plate with four home runs, a double, eight RBI and an A.L.-record 18 total bases in a 10-3 Rangers' victory at Oriole Park at Camden Yards. The four-homer performance was a first for the Rangers and it was the Majors' first four-home run game since Toronto's Carlos Delgado on September 25, 2003. It marked the 30-year-old's sixth career multi-homer game, and the first time that he homered more than twice in a game. Hamilton's eight RBI also shattered his previous career best of five (three times), which he last accomplished in an April 17th tilt against the Boston Red Sox at Fenway Park.
Read more about the Rangers at Lone Star Ball.