Understanding the Math

Understanding the Math

            If you’ve read any of my work from to this point then you’ve probably noticed that I like sabermetric stats and love to using them to explain players and teams.  To this point I really haven’t explained the stats that I use so it seems like a good time to start.  Today we’re going to start with the basics and move up to the more complicated stats, the goal of these will to educate people that don’t really know the stats and to let you be able to calculate them yourself.  Today we’ll start with the most basic stats: the slash line.

Batting Average

AVG: H/AB

            One of the most common stats people look at and gauge a players value.  To me and many other staticians out there this is the worst stat to gauge a player on since it leaves out so many variables.  Example: If a player has a .290 AVG and gets a sac-fly his AVG is still .290 but he made an out.  Likewise BA puts all hits on an equal playing field.  To BA a single is just as valuable as a triple or home run, that just isn’t true what so ever.  It is a fine enough stat to just look at as a quick “oh how’s this guy doing” but there are better stats to actually gauge how he’s doing.

On-Base-Percentage

OBP=H+BB+HBP/AB+BB+HBP+SF

            Very commonly referred to as the “Moneyball” stat since it was the main stat used by Billy Beane.  OBP is a far better gauge of a player’s abilities since getting on base is by far one of the best skills a hitter can have.  Though much like AVG this has some flaws.  OBP values every hit as equals just like AVG does all it does differently is add walks and other stats that have to do with getting on base.  The walks are the big thing since a good OBP tends to come from guys that can take a walk often enough.

Slugging

SLG=(Singles+(2*Doubles)+(3*Triples)+(4*HR))/AB

            Commonly looked at as the “Power” stat but in reality it takes the total number of bases and divides it by the number of at-bats.  For what it does it does it well and shows a pretty decent look at a players ability to round the bases.  Again this stat doesn’t tell the full story and is not the perfect stat to gauge a player.  It doesn’t take things like walks into account and things like sacrifices hurt your SLG overall.

Averages of the last 5 years

	AVG	OBP	SLG
2013	.253	.318	.396
2012	.255	.319	.405
2011	.255	.321	.399
2010	.257	.323	.403
2009	.263	.333	.418
Total	.257	.323	.404

            Here’s the list of the last 5 years averages of AVG/OBP/SLG just to help you get a picture of what the average is.  As you can see there’s been a pretty steady decline in the 3 stats since 2009 and that doesn’t seem like it’s going to change any time soon but the reasons for that lie in other stats that I’ll cover later on.  For now this is just a quick look to see the trend and to see what the average looks like.

            With all that I’ve said there was one point I kept bringing up, each stat had a flaw and didn’t tell the full story.  Even OBP, which I do like a lot and I value more than both AVG and SLG, had flaws and didn’t give the full story.  Here’s the surprise of the article there is no ONE stat that gives the full story.  Stats run best when you use more stats to get a bigger picture.  AVG/OBP/SLG have flaws when you use one solo but when you use all three to get the picture then it becomes much clearer.