When your starting second basemen has smashed 154 HRs over the last 5 years and begins the season with a .180/.250/.335 line, you begin to worry. Uggla's 59 wRC+ isn't the worst among second basemen in the majors, but Chris Getz, Orlando Cabrera, and Omar Infante have out-performed his offensive "contributions" (apologies to the lone trailer, Mark Ellis).

But we know that he's been terrible. What we want to know is what we can expect from him in the future. Although we can't get back the 52.8 million dollars we're going to pay him over the next 4 years (2012-2015), we might get back the type of performance that justified that 4-year extension. 

Uggla has had a terrible start and a brief glance at his advanced stats suggests improvement. Prior to Wednesday's game Uggla had a .197 BABIP and a .291 xBABIP, a batted ball profile that indicates he has been unlucky, and a profile just below his career .296 BABIP.

However, a closer look at his profile reveals a more discouraging outlook for Uggla. This reveals a line drive rate of 14.6% (career 16.5%), ground ball rate of 46.4% (career 38.1%), and fly ball rate of 39.1% (career 45.4%). Given the trade-off of fly balls (which generally fall in less for hits)  for ground balls (which generally more often fall in for hits), it is not surprising that Uggla has a similar expected batting average on balls in play (.291) to his career BABIP (.296), despite the lower drive line rate. But can we really expect a .291 BABIP going forward if these trends continue?

Looking at the grounders, the league-average player bats for a higher average on grounders than fly balls, but that doesn't mean this difference is the same for every player. Like most of the Braves, Dan Uggla is slower than average and should not expect to get to as many hits as his peers do on ground balls. So, in Uggla's case, grounders aren't as valuable and you can safely reduce a few points off Uggla's xBABIP.

In terms of fly balls, 15.2% of Uggla's have left the yard during his career, which means that fewer of his fly balls are reflected in his yearly BABIP than most hitters. However, this year only 11.9% of Uggla's fly balls have left the yard, meaning that more fly balls will be included in his BABIP (which excludes home runs), thus lowering what we can expect for his BABIP going forward. Furthermore, Uggla has popped out on 10.2% of his fly balls this year compared to 8.4% of the time during his career, which his xBABIP does not account for.

Unless Uggla somehow changes his batting profile (either through his approach, mechanics, or something else), his speed, lack of home runs, and increased pop outs all lead to the conclusion that his xBABIP won't be quite as high as his .291 xBABIP suggests, and that it will be much lower than his .296 career BABIP.

These aren't extreme changes, but the trends aren't encouraging. He gets most of his value for frequently hitting enough fly balls hard enough to leave the yard. If he's not doing this we'll still be wondering if his name is Dan.

Sources: Fangraphs, Cot's Contracts