Minor mechanical flaw source of Span's 2010 offensive woes?

There have been plenty of theories thrown around this off-season attempting to identify the reasons behind Denard Span's 2010 statistical regression:

He's been hitting with two-strikes more frequently.

The transition to natural grass from turf has shaved points off his batting average.

He played too much and needed more rest.

While all of those were factors to some extent, more tangibly, Twins Hitting Coach Joe Vavra recently acknowledged a slight flaw in his mechanics last year that he believed contributed to his offensive woes.

In conversations with Vavra on the subject of Span, 1500ESPN's Phil Mackey wrote that Vavra attributed the increase in grounders on the center fielder not keeping his head as still as he had in previous season:

Reviewing video footage of Span's swing dating back to 2008, there is ample visual evidence of additional bouncing this season. Comparative to his two prior years, Span's 2010 mechanics demonstrate a wellspring of pre-swing movement:

Clearly, the pre-swing movement needed to be ironed out and toned down if Span hopes to get back on track as one of the game's best lead-off hitters and, judging from Vavra's comments, it sounds like that was a big focus this spring. Yet, I'm not entirely convinced that the bouncing is the only influential factor for his regression.

Last May, after Span trudged into the first two months of the season with an absurdly high groundball rate, I noticed that he was positioning his hands slightly different than he had in the past. Because of Vavra's comments, I went back to explore some of the footage.

As you can see from the side view, Span's starting point with his hands has shifted noticeably since his rookie season:

In 2008, Span kept his hands fairly low, well below his front shoulder level while leaving his bat almost perpendicular to the ground. The following year, Span transitioned to holding the bat higher with his bottom hand parallel to his front shoulder. Additionally, he cocked the bat slightly at an angle towards his head. Meanwhile, this past season, while maintaining a similar level, Span wound the bat even further behind his head.

I'm not going to pretend to be Joe Vavra and say I know why Span made the adjustments. This progression could have been designed in order for Span to generate more power in the hopes of creating a whip effect in this swing. Likewise, the alteration may have been added to improve his zone coverage as raising his hands also gives him the ability to handle pitches up in the zone better. Then again, it could be that Span simply felt more comfortable at the plate that way.

Denard Span's production and power versus fastballs

Runs Above Average

Slugging Pct

2008

12.4

2009

6.7

.377

2010

-9.5

*via Fangraphs.com & MyInsideEdge.com

In 2008, his first season with the Twins, Span blasted away on heaters. In 280 plate appearances that ended on fastballs that season, the lefty hit .313/.425/.467. The following year, with almost double the amount of plate appearances, Span hit .303/.390/.377, a sizeable drop in power for sure. Certainly, the jump in sample size could have an effect on the overall numbers but in 2010, the returns on fastballs dropped once again for Span as he hit .272/.356/.348.

Could drawing his bat back further each year have led to this decrease?

I'm not trying to make any definitive connections, rather I'm simply suggesting where there is smoke, there's fire. Because Span has experienced incremental decline in his power numbers the past two seasons – particularly against fastballs – one has to wonder if the slightly longer swing is, at the very least, partially responsible as well. To me, while Vavra is untangling one aspect of his swing in Florida, it appears that there is another element of his mechanics that may need some addressing too.