Fastball Woes May Punch B.J. Upton's Ticket to Gwinnett

B.J. Upton signed a five-year, $75.25 million free agent deal with Atlanta over the winter, the largest contract handed out in franchise history. This time next week, Upton could be the wealthiest guy to ever suit up for the Braves -- the Gwinnett Braves. Manager Fredi Gonzalez and the front office are debating whether to ask the 27-year-old to accept a demotion to Triple-A. Upton has enough service time in the majors to reject the move, but he is off to an historically wretched start at the plate. B.J.'s 31 OPS+ is the worst for a Braves hitter getting at least 150 plate appearances in a season since John Russell (30 OPS+) in 1989.

If Upton does end up with the G-Braves, it'll be because he's chopping fastballs he normally pulverizes into the dirt. His groundball rate against heaters has jumped by nearly 20 percentage points this year, from 35% in 2012 to 53% in 2013. The big league average, by the way, is 44%.

Upton's ground ball rate vs. fastballs, 2012

Upton's ground ball rate vs. fastballs, 2013

All of those grounders have put a huge dent in Upton's slugging percentage against fastballs, which has fallen over 300 points from last year's .533 mark. In fact, Upton has outslugged just Miguel Montero and the recently-demoted Dustin Ackley versus fastballs this season:

Lowest fastball slugging percentage, 2013 

Upton has been somewhat unlucky this season (his batting average on balls in play is just .204, which is 90 points lower than in 2012), but his complete lack of punch against fastballs is disturbing. B.J. and Braves hitting coach Greg Walker are working on swing tweaks that would reduce the load in Upton's swing. Atlanta needs those sessions to pay off. First-place status and Upton's record paycheck aside, the Braves can't afford to keep him in the lineup when he's hitting like this.