Simple Sabermetrics: OBP and SLG


Country Breakfast will spend a lot of time on base the this year.

Sometimes it’s OK to talk about the basics. I’m playing in a league this year with the a few of the writers from ESPN and in lieu of home runs and batting average as scoring categories, both on base percentage and slugging percentage are used. Let’s use this as an opportunity to talk about both on base (OBP) and slugging (SLG) percentages, and how understanding these two statistics can help you build better fantasy baseball teams.


OBP has been an official MLB statistic since 1984, so it’s odd to talk about it in context of sabermetrics, but again, we’re keeping things simple and you’d be surprised at how many people haven’t really thought about how it’s calculated or why it’s useful to understand. (I promise in the future we’ll graduate up to wOBP, a great statistic focus on linear weights).

On-base percentage is calculated using this formula:

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

  • H = Hits
  • BB = Bases on Balls (Walks)
  • HBP = times Hit By a Pitch
  • AB = At bats
  • SF = Sacrifice Flies

This is how often a player gets on base, not counting errors, a fielder’s choice, or anything like that. A team only gets 27 outs in a game, so needless to say, getting on base is vitally important, and the reason that this may be used in your league as a scoring category.

I’m a fan of back of the napkin math, so don’t hesitate to assign a simple constant for sacrifice flies or the number of times a player is hit by a pitch. Sure it’s not exact, but it’s gets you in the ballpark so to speak, and allows you to quickly scan walks to get an idea of the leagues best performers.

The league average has fluctuated over the years. It’s gone from a dead ball .300 to around .340 in our modern area. (The Splendid Splinter Ted Williams is the all time career leader at .482, meaning for his career he made an out barely half the time, while the single season best was Barry Bonds‘ 2004 season, which ended with him having a .610 OBP. Let that sink in.)

So guys adept at getting on base will come in above .340, while your no walk knuckleheads will often time be below .300 even.  Set your fantasy baseline at the .340 league average, knowing that drafting guys above that gives your best chance to compete in the category.

Joey Votto will lead the Majors in 2013 at or around a .420 and it really won’t be close, but Prince Fielder, Miguel Cabrera, Joe Mauer and Buster Posey will give you a strong showing. Billy Butler, A.J. Ellis, Shin-Soo Choo, Dexter Fowler, Carlos Santana, Miguel Montero, and Alex Gordon are some lesser names that will also give you a strong showing in the category.


Slugging is a measure of hitting the crap out of the ball. Slap bunting singles hitters need not apply. It’s calculated by:

"SLG = (1 x 1B) + (2 x 2B) + (3 x 3B) + (4 x HR) / AB"

Walks are excluded and you can see that a player is rewarded for their total bases. In fact, it can be simplified to TB (total bases) / AB.

Babe Ruth retired with a .6898 slugging percentage. Ted Williams and Lou Gehrig followed with a .6338 and .6324, respectively. The highest active career SLG is Albert Pujols at .6079, which barely nudges Barry Bonds‘ career .6069.

Miguel Cabrera is likely to lead the Majors in 2013, but Ryan Braun, Giancarlo Stanton, Jose Bautista, and Josh Hamilton will be near the top of the leader board. Sneaky good with be Mike Napoli, Ike Davis, Josh Willingham, and Allen Craig. Again, these aren’t singles hitters. They hit the ball over the fences or drive it into the gaps, meaning there is a strong correlation with RBI as well.

On day we’ll talk about ISO, which pulls singles out of the equation and is a even better measure of a player’s true power, but I hope this basis primer was helpful for those who may play in a SLG league.

Here are other some other posts in the Simple Sabermetrics series: Command Ratio, FIP