Several times on this blog, we’ve engaged in debates over the meaning behind batting average for balls in play. While we can draw a consensus as to how it relates to pitchers, far too often, the statistic is misrepresented as meaning the same thing for batters.

Lazy analysis treats a high or low BABIP as a sign that a hitter experienced a lot of good luck or bad luck. While certainly randomness plays a factor in the success and failings of a plate appearance, one cannot look at BABIP alone as a means of deciphering the influence of luck on a batter.

As our friend Jon Hale once wrote:

It would be like saying that a spike or fall in batting average has to be luck, because for hitters, BABIP is just the same damn thing with K’s and HR’s removed from the equation (really two of the last things you want to exclude when trying to decode if a streak or slump or bad year is due to something tangible). While it is true that if a player has an extremely uncharacteristic BABIP over a period of time, those results should be taken with a grain of salt, you could just as easily say that about batting average because they’re practically the same damn stat. Obviously, nobody would call every .200 hitter a victim of luck — all that’s really going on here is that if you don’t hit somewhere in the realm of league average, you’re not going to get major league at-bats for long.

This type of examination of BABIP is of particular interest when discussing Toronto Blue Jays center fielder Colby Rasmus. For the St. Louis Cardinals in 2010, Rasmus had the third highest wOBA in all of baseball among center fielders, behind only Josh Hamilton and Carlos Gonzalez. Ditto for OPS. Then, in 2011, he collected the second worst wOBA among qualified center fielders in the league, trailing only the disastrous season of Alex Rios.

So, what caused the change?

Calling for the most attention from his list of numbers over the last two seasons is a BABIP that went from .354 in 2010 to .267 in 2011. That’s an incredibly sharp decline from one season to another, but as we discussed above, it’s not to be dismissed as merely the result of random occurrences.

The further into the numbers we look, the more we see that a reduced BABIP wasn’t causing Rasmus’ terrible season as much as it was a symptom of his bad year. Ultimately, two major factors were leading to a lower batting average for balls in play: 1) He’s getting fooled by change ups low and away far more often than last season (10.1% whiff rate on change ups in 2010 compared to a 18.1% whiff rate on change ups in 2011); and 2) he didn’t hit the ball as often the opposite way.

Let’s begin looking at these two factors by comparing how Rasmus handled the 316 change ups that were thrown his way in 2010 to the 232 that he saw in 2011.

Exhibit 1A is a chart of the change ups that he swung at in 2010 (49.1%):

Exhibit 1B is a chart of the change ups that he swung at in 2011 (57.8%):

As might be expected from swinging at 8.7% more change ups, Rasmus also drastically increased his whiff rate on the pitch, as I mentioned earlier. Overall, his plate discipline numbers weren’t nearly as bad, as his whiff rate went from 10.9% in 2010 to 11.0% in 2011. Rasmus was swinging at 48.2% of the pitches he saw in 2011, compared to 45% in 2010, but making contact with 76.8% of the pitches he swung at in 2011, compared to 75.8% in 2011. In other words, he was making more contact, but in a less efficient manner last season, which saw him reduce both his walk and strike out rate in equal numbers.

By swinging at more pitches, Rasmus traded strike outs from the prior season with poor contact. Unfortunately, he also traded some of his walks for poor contact, reducing his line drive and fly ball rate while increasing his ground ball rate and most disappointingly, his infield fly ball rate as well. His 15.5% infield fly ball rate was the seventeenth worst out of 145 qualified batters.

However, nothing really shows how Rasmus’ poor decision making led to poor contact quite like the difference in the change ups he took in 2010 versus 2011.

Exhibit 2A is a chart of the change ups that he took in 2010:

Notice the large amount of change ups he took for strikes in 2010, and then, Exhibit 2B is a chart of the change ups that he took in 2011:

While the differences between a proper strike zone and a realistic strike zone can seem rather large for a left handed hitter, it’s not an exaggeration to suggest that Rasmus was willing to bypass change ups to get to a pitch he could drive in 2010, compared to 2011 when he attempted to make contact on far more pitches anywhere near the zone.

This wasn’t caused simply by Rasmus seeing more change ups with two strikes either. Rasmus was making a conscious effort to swing at pitches that typically don’t result in the best contact on counts when he simply didn’t have to make those swings. This would certainly lead to whiffs, as well as bad contact when it was eventually made, but it doesn’t end there.

Let’s take a look at where the batted balls from Rasmus were actually going.

Exhibit 3A is a spray chart from 2010:

To be compared with Exhibit 3B, a spray chart from 2011:

Notice not only the lack of base hits to left field, but also the power to center field and right center field that Rasmus seems to exhibit in 2010, only for it to disappear in 2011. This sudden change has resulted in something of a damaged reputation for the 25 year old.

Kevin Goldstein of Baseball Prospectus recently spoke to eight baseball executives about unsigned Cuban prospect Yoenis Cespedes, comparing the free agent to five different young outfielders. Six of the eight front office types believed that Cespedes had a brighter future in the league than Rasmus.

While the reasoning behind such stances could be laughable – “There’s something about the J.D. Drew way he goes about things.” – it was ESPN’s Keith Law who provided the best insight as to why consensus wouldn’t be more favourable to Rasmus, a year removed from being one of the best players at his position, when he described the left handed hitting center fielder as thus:

Lot of work to do there on his mechanics, especially his lower half. Tools and approach are still there for stardom.

Admittedly I’m not a scout, but comparing video and pictures of Rasmus batting in 2010 to his plate appearances in 2011 reveals a noticeable change in his swing, wherein his upper body seems to be ahead of his lower body as he shifts weight. Typically, the transfer of weight into a swing should result in the batter revealing the bottom of the foot on his back leg straight behind him as he makes contact.

This is a picture of Rasmus just after the moment of contact:

His legs seem very close together, and his back hip hasn’t rotated into his movement in a way that would maximize the speed and power of his swing.

Compare this to the moment of contact from the previous year when he starts his at bat with a far more open stance that forces him to transfer his weight:

While still not ideal, at least we can see that his momentum has transfered enough so that there’s far less weight on his back foot as his bat makes contact with the ball (remembering the difference in camera angles between these two shots).

Perhaps this explains the weak contact that’s resulted in less hits when Rasmus went the other way in 2011 versus 201o. While the center fielder may be strong enough to power base hits and home runs into right field with his arms alone, when going the other way, he’s rendered incapable without his entire body moving into it.

As we see, not only is there a cause for the decrease in BABIP that extends beyond mere random occurrences, but those causes can be complicated. It’s pure speculation, but I wonder if Rasmus had been getting frustrated with the lack of results due to his upper body being ahead of his lower body, which has in turn led to poor plate discipline, most notably when facing change ups. Throw in an injury that could’ve been hindering his flow at the plate, and it’s easy to understand why not only a change of scenery, but a fresh start on a new team in a new season could revive Rasmus back from his recent struggles and into once again becoming one of the elite performers at his position.

Of course, this is the positive view. One might also recall the problems that erupted between Cardinals manager Tony La Russa and Rasmus when it came to his approach at the plate, and perhaps it’s the more “J.D. Drew aspects” of his personality that get in the way of his receiving instruction. This might lead one to believe that the revival that Toronto Blue Jays fans hope for might not be as easy to come by.

Like many members of his team’s roster, Rasmus is something of a question mark. I’ve written in the past about the upcoming year being one of discovery for the Blue Jays, and that’s probably best represented by Rasmus. If he pans out like in the positive scenario given above, it will be a major step forward for the team. If he doesn’t, it wouldn’t be surprising to see Toronto possibly move toward a different direction ahead of 2013. This will be a very interesting season for Rasmus, and one that should be thrilling to watch.

Update: For people who like potentially good news, here’s a video of Rasmus taking batting practice late in the year during his rehab stint at New Hampshire from reader Sami. Notice the bottom of his back foot being revealed as he makes contact.