Who is Justin Upton -- the guy who hit 31 home runs in 2011 and seemed set to join baseball's inner circle of sluggers, or the guy who went deep just 17 times in 2012 and drew the ire of Uptown? GMs must ask themselves this question before piecing together a trade package for the 25-year-old, who is once again on the market according to Ken Rosenthal of Fox Sports. If Upton is to re-establish himself as one of the game's great young talents, he'll have to cut back on the power-sapping ground balls that became all too common in 2012.
In 2011, Upton's ground ball rate (about 37%) was far below the average for big league hitters (about 44%). He rolled over when he chased below the knees, but he otherwise put the ball in the air more than the average hitter:
Upton's ground ball rate by pitch location, 2011
In 2012, however, Upton hit far more grounders on low and low-and-away offerings:
Upton's ground ball rate by pitch location, 2012
His ground ball rate spiked to a league-average 44%, as pitchers pounded him at the knees more often. Upton got a low pitch half of the time in 2012, up from 46% in 2011 (the MLB average is about 41%). He had the biggest increase in grounders on breaking stuff:
Upton's ground ball rate by pitch type in 2011 and 2012
It's possible that Upton has already started to adjust to the deluge of low pitches: He decreased his ground ball rate to 2011 levels during the last month of the 2012 season (36%) while hitting six homers and slugging north of .500. Upton has to keep lofting pitches to tap into his considerable power, no matter what uniform he's wearing next spring.