In 2007, B.J. Upton hit .300/.386/.508 with 24 home runs, 22, stolen bases, 86 runs and 82 RBI in 474 at-bats. It has been downhill since.
Technically, Upton did improve some in 2010. He hit 18 home runs to go along with 42 stolen bases, but his .237 AVG continued to frustrate fantasy GM's. Part of the reason for the low AVG's are Upton's high strikeout totals. That, combined with consistently low line drive rates, make it tough for a hitter to hit for a high AVG without some significant help in BABIP. The chart below shows Upton's line drive, strikeout and swing and miss numbers from 2007 through 2010.
Upton, not being a true power hitter, has a lot going on with his swing that could account for his struggles.
Standing almost completely upright in the batter's box, Upton starts his swing with not so much a stride, but a hitch in his front leg. His leg lifts straight up with his knee slightly bent, but doesn't move forward. In fact, the hitch tends to get Upton even more upright than his initial stance. The biggest technical part to this hitch is Upton's front foot. The foot rotates almost 90 degrees backward pointing toward the catcher. This creates two problems in particular.
1. It is a timing mechanism, so Upton's timing has to be spot on or a good fastball will beat him.
2. It can cause his hips to open or rotate too soon, leaving his hands behind on the pitch.
On the flip side, Upton has always hit the curveball well and, for the most part, changeups too. This is likely due to his hands being a bit late through the zone. Advanced statistics from Fan Graphs
The "w" in front of the pitch abbreviation denotes runs above average. FB = Fastball, SL = Slider, CT = Cutter, CB = Curveball, CH = Changeup.
You can see from the image below how Upton's hips clear before he starts his hands.
At this point, everything is behind, even his pivot foot seems late.
On this particular pitch, Upton's timing is spot on and he is able to get his hands extended on a Scott Kazmir fastball (is that really saying much?).
Compare his contact point in 2010 to his contact point in April of 2008. In the first picture below (2010) we can see how his front foot is flying open a bit and more weight is distributed toward the heel. Then notice the second and third pictures below (2008) how his front foot is flat on the ground and a bit closed. His weight is also more centered throughout his body.
Upton hit .273 in 2008 with a 19 percent line drive rate, 50 percent ground ball rate and the highest contact rate of his career as a regular, but he only managed nine home runs. However, Upton was suffering from a shoulder problem most of that season -- he aggravated his shoulder in May after hitting .293 with three home runs in April.
We can see a clear difference in Upton's spray chart, especially with regards to home runs. In 2008, the majority of Upton's balls in play to left field turned into hits. Unsurprisingly, his fly ball rate has risen every season since 2008 and more of his balls in play to the outfield have become outs, especially to left, left-center and center.
Most of Upton's power now comes to the pull field. This is a result of two things.
1. When Upton rotates (opens) his hips early, he clears room for his hands to pull through on inside pitches. As long as his timing is on, this helps him get the barrel out in front.
2. If his hands are late -- due to his hips rotating early -- it actually helps him against inside offspeed pitches as his hands can "catch up" to a slower offering.
The problem is that Upton's success mostly stems from timing, which is something his mechanics hinder. Because he has so many moving components (ankle twist, bent knee during stride, hand movement before swing and hips that open before his hands approach the ball), Upton fails to find consistency in his timing. This had led to consistently high swing-and-miss rates, high strikeout rates and low line drive rates.
For Upton, getting back to basics might be a good idea. Even if he can't break the habits with his ankle twist and pre-swing hand movement, he can work on little mechanical improvements like keeping his front side in and staying on the balls of his feet rather than turning on the heal of his front foot. Simply staying closed more often should translate to more opposite field power and more line drives overall.
Even with mechanical corrections, Upton may never hit for a high AVG, but something better than .240 would significantly increase his value in real life and fantasy baseball.