Coming into the 2013 season, few would have pegged Brandon Belt to be the 6th most valuable first baseman in the league by season's end. Yet he did, and to many he finally lived up to his prospect hype. He finished the year with a 4.1 fWAR, which barely came short of Edwin Encarnacion and a tad ahead of Mike Napoli; suffice to say his 2013 was really good. The questions then become how did this happen? And is this a sustainable performance going forward?

If we take Belt's performance at face value there's a lot to like. He hit career highs in nearly every relevant offensive metric and made some progress in his defense as well. However a deeper look into his peripherals suggests this performance might be suspect in the future.

The first area I investigated was to see if the power spike was real. Belt's ISO jumped from .146 in 2012 to .193 last year; which would normally indicate a real jump in power. However, if we look at his average batted ball distance, via Baseball Heat Maps, the gap is much smaller. In 2012 his batted ball distance was 279.05 Ft, in 2013 283.81 Ft, while better, it's not by much. Additionally, his HR/FB % sat at 10.6%, which is around league average and ranked 22nd of 25 qualified first basemen and 76th in all of baseball last year. Furthermore, his average actual distance per home run, via ESPN Home Run Tracker, didn't change much either. In 2012 he registered at 393.1 Ft and in 2013, 394.8 Ft. Again, there is some improvement, but very marginal and not enough to validate the ISO spike. Finally, ESPN's Home Run Tracker contextualized 10 of his 17 home runs as "Just Enough", which means he probably got his fair share of luck in the home run department last year.

However, home runs might not have been the only area in which he got lucky. As I said earlier, if we take his season at face value, it's nice, but if broken up, there's more to the story. Up until the All Star break last season, Belt's season was nothing out of the ordinary and right in line where you'd expect him to be. His triple slash was .260/.336/.448, good for a .341 wOBA, which ranked 14th among qualified first basemen. Yet, in the second half he seemingly found new life, slashed .326/.390/.525, good for a .396 wOBA and 4th among first baseman, only behind Freddie Freeman, Paul Goldschmidt, and Joey Votto. How did this happen? Well, as you might have already guessed, a BABIP surge of .392 in the second half compared to his .319 in the first half. While a BABIP spike isn't a nail in the coffin, but rather, it just makes his performance to be taken with a grain of salt.

One thing I will note though is, his BABIP in 2012 and 2013 are identical at .351 and also in 2012 he achieved a second half BABIP surge .367 compared to .331 first half. Perhaps Belt's 2013 second half was regression to the mean or Belt is a "second half" guy, however I'm not so inclined to believe either because of the aftermentioned points. And because of this I'm bearish on Belt next year. I do believe he can still be a solid 2.5 fWAR guy and numbers closer to 2012 are more what to expect, but expecting any more seems like a stretch.

All stats derived from FanGraphs, Baseball Heat Maps, & ESPN Home Run Tracker.