Why hasn't Justin Upton signed yet?

Justin Upton is still unsigned this offseason.

Why? The possibilities are endless. Maybe teams are balking at his asking price. Maybe he's waiting for Yoenis Cespedes and Dexter Fowler to sign so that he could be the last big free agent outfielder left. Maybe teams are valuing that draft pick they'd have to give up to sign him. Maybe he secretly retired. Maybe this is like the ending to Fight Club [Ed's note: spoiler alert!] where we realize that Justin Upton never really existed, and he was really just Melvin Upton all this time.

Maybe, though, the holdup has to do with Upton's on-field performance. Are there any trends in his statistical profile that might scream, or even whisper, "Concern!" and help contribute to the lack of interest in Upton thus far this off-season?

There are many, many reasons to like Justin Upton. First of all, he's durable, and teams generally pay more for certainty. Upton has played in at least 133 games in each of the last seven seasons. The only other outfielder to do that? 42 year-old Ichiro Suzuki. In addition to being on the field nearly every day, Upton is also incredibly consistent: he's posted a wRC+ of at least 109 in each of those seven seasons. Possibly overlooked in his remarkable consistency is that Upton has been consistently well above average, posting a wRC+ of 120 or better in five of the last seven seasons. He provides a satisfying combination of on-base ability and power; his career OBP of .352 compares quite similarly with that of noted on-base-getter Jason Heyward (.353 career OBP), while his career slugging percentage and ISO are both better than those of, say, Adam Jones. He also helps on the basepaths (career 30.5 Fangraphs baserunning runs above average, never a season with a negative BsR) and doesn't hurt on defense (career UZR/150 of exactly 0.0), which adds up to about a four WAR player. Unlike most free agents, Upton is still oozing with potential, as he was a former number one overall selection not too long ago and will play most of next season at age 28. For reference, Cespedes and Fowler will both be 30 by Opening Day 2016. I'd also be remiss not to mention Justin Upton's cool name, which doubles as the couple name for Justin Verlander and Kate Upton.

All of this is a long-winded way of saying that Justin Upton is good at baseball. He's an above-average player who is still in his prime and just put up a season in line with his career averages. Why wouldn't teams be clamoring for him?

Well, for one thing, Upton's 2015 actually revealed some rather troubling trends. His .304 BABIP was the lowest of any full season in his career; not only was it lower, it was drastically lower than his career .329 mark. Normally, that'd be a good sign for a bounceback, but it's quite troubling when examined in conjunction with his batted ball data. Batted ball data has its flaws and is not meant to be a be-all, end-all stat (no statistic is), but it helps paint a picture. His line drive percentage of 17.3% was the lowest of any full season of his career, over two full percentage points below his career average. He had topped 20% in each of his last three seasons. And the lack of line drives were not evenly distibuted; his GB% stayed constant and all of his line drives turned into fly balls this season, which helps explain that lower BABIP. He also posted the lowest contact% of any of his seven full seasons in the bigs as well. In summary, Upton made less contact in 2015 than in any full season in his career; and when he did, he barreled it up less frequently than in any full season in his career.

Unfortunately, the bad news doesn't stop there. His wOBA was also the lowest of his career. "But hey!", you might say, "wOBA isn't park-adjusted! By wRC+ he was right in line with his career! Take him out of Petco and he'll be just fine!" To which I'd reply two things:

1) Lower your voice; there's no need for so many exclamation points.

2) Yes, you're half right. Adjusting for park, he was in line with his career averages. However, he actually posted better road splits, and any team besides the Padres would be taking him away from Petco Park --

Home: .277/.360/.506, 147 wRC+

Road: .225/.312/.402, 92 wRC+

The final piece of bad news is Upton's platoon splits. Until this season, he has always shown normal platoon splits. However, in 2015, Upton had himself quite a tough time against lefties, posting a ghastly .191/.258/.300 slash line to go along with a 58 wRC+ and a Chris Carter-ian 32.2 K%. However, platoon splits usually take 1,000 PAs against each hand before stabilizing, so we can hopefully write the reverse platoon splits off as small sample size noise.

On their own, none of these trends are disturbing enough to warrant staying away from Upton. And I can't stress enough the monumental gap between "Justin Upton, worse hitter" and "Justin Upton, bad hitter". But the confluence of these negative trends, to go along with little-to-no positive trends from this season, may be making teams think twice before dialing Upton's agent.

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Austin Yamada is a contributing writer for Beyond The Box Score.