Is there such a thing as an "April advantage" in baseball, and if so which side—hitters or pitchers—has the edge in the season's first month? With the calendar flipped to April and the 2014 regular season already underway, now is as good a time as any to explore this concept.
To do so, we took a look over the past five years—the 2009 through 2013 seasons—and found the averages for hitters in several key statistics from the month of April* and compared those to the league-wide averages in the same metrics over the course of the entire season. This was achieved by using FanGraphs' nifty statistical database.
*Technically, the numbers come from March and April, because that's how the splits are most easily spliced, but only a very small percentage of Major League Baseball games actually occur in March.
Let's start with the hitters and then jump over to the pitchers.
Here, then, is a look at hitter performance from each of the past five Aprils in a number of categories, along with hitters' overall performance in those same categories over the entire year as shown in the row below:
|Hitters: League-Wide Statistics in April vs. Full Season (2009-2013)|
|April 2013||.255/.322/.408||.729||.295||.153||11.0 %||.320||8.3 %||19.6 %|
|All 2013||.257/.322/.403||.725||.299||.146||10.6 %||.318||8.1 %||19.3 %|
|April 2012||.253/.321/.404||.725||.292||.150||10.6 %||.316||8.4 %||18.8 %|
|All 2012||.259/.324/.413||.737||.299||.154||11.4 %||.320||8.1 %||19.2 %|
|April 2011||.254/.324/.399||.723||.291||.144||9.2 %||.318||8.8 %||18.1 %|
|All 2011||.259/.325/.406||.731||.297||.147||9.7 %||.321||8.3 %||18.1 %|
|April 2010||.259/.335/.413||.748||.297||.154||9.7 %||.330||9.6 %||17.9 %|
|All 2010||.261/.330/.410||.740||.299||.149||9.5 %||.326||8.7 %||18.0 %|
|April 2009||.267/.345/.428||.774||.301||.162||10.2 %||.339||10.0 %||17.2 %|
|All 2009||.266/.338/.425||.763||.301||.159||10.2 %||.334||9.1 %||17.5 %|
First of all, let's point out here that what's great about using FanGraphs for this is that the data can be manipulated so as to exclude pitchers from the hitting element, which only waters down the numbers (and looks silly most of the time, if we're being completely honest).
Secondly, the statistics chosen are all of the rate and ratio variety, which makes it easier to compare a one-month sample to a six-month sample. Trying to use raw numbers for this wouldn't be helpful unless they were broken down to a per-game basis.
Now then, what are the takeaways? Well, as you might be able to infer, the highlighting indicates whether hitter performance was better in April or better over the entire season. Given that bit of information, it's easy to see that hitters actually came in above their respective full-season average in Aprils of 2013, 2010 and 2009.
Maybe not quite what you expected, huh?
Of course, none of the disparities from April compared to April through September are all that egregious, but we're also talking about tens of thousands of plate appearances in any given month and hundreds of thousands over a full season. So, yeah, even differences that appear minor do add up over such large samples and extended periods of time.
OK, now for the pitching side of things. Here's a breakdown of overall pitchers' performance in several metrics from April of each of the past five seasons compared to the rest of the year:
|Pitchers: League-Wide Statistics in April vs. Full Season (2009-2013)|
|April 2013||3.93||3.97||1.30||.290||20.2 %||8.2 %||2.46||10.9 %||1.26|
|All 2013||3.87||3.87||1.30||.294||19.9 %||7.9 %||2.51||10.5 %||1.30|
|April 2012||3.84||3.98||1.29||.286||19.3 %||8.2 %||2.34||10.5 %||1.33|
|All 2012||4.01||4.01||1.31||.293||19.8 %||8.0 %||2.48||11.3 %||1.33|
|April 2011||3.90||3.95||1.31||.286||18.6 %||8.6 %||2.16||9.1 %||1.20|
|All 2011||3.94||3.94||1.32||.291||18.6 %||8.1 %||2.30||9.7 %||1.24|
|April 2010||4.20||4.19||1.38||.292||18.4 %||9.4 %||1.95||9.6 %||1.21|
|All 2010||4.08||4.08||1.35||.293||18.5 %||8.5 %||2.17||9.4 %||1.18|
|April 2009||4.58||4.50||1.44||.295||17.7 %||9.8 %||1.80||10.1 %||1.11|
|All 2009||4.32||4.32||1.39||.295||18.0 %||8.9 %||2.02||10.1 %||1.15|
Same deal applies—the highlighting shows whether pitchers were better in April or better from April through September.
In case it's not immediately clear, the pitching stats are the exact inverse of the hitting stats. Which is to say, when the hitters were better in April of a particular season, the pitchers were worse that same April—take a look at 2013 in both tables again, for example.
On the other hand, when pitchers were better in April, the hitters were worse, which is what happened in 2011 and 2012. This, of course, makes all sorts of sense when you think about it for even a brief moment.
Again, though, it needs to be made clear that while there are differences and fluctuations, they are very slight.
The bottom line that can be drawn from all these numbers? Unfortunately, there's no cut-and-dry answer about which side holds the edge in April over the past handful of seasons, based on what the statistics above show.
So while you might have expected pitchers to have an advantage early on relative to the rest of the season—perhaps wanting to attribute as much to the idea that batters need an adjustment period to get their timing down or even that the colder weather might make hitting more challenging by limiting hard contact as well as the flight of the ball—the results don't always bear that out, at least in recent years.
About the only definitive conclusion that can be made is that pitching has been taking over the sport since 2009. But then, you probably already knew that.
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