The Formula For Batting Average

In our continuing series on the basics of betting baseball we turn our attention to MLB Hitting Acronyms. That is, commonly used metrics that handicappers and major league analysts utilize to evaluate offensive power. The purpose of this article is to explain in layman's terms what several of the widely used acronyms such as AVG, OBP, SLG, and OPS mean. For each of the different metrics defined below, we include the MLB Average, MLB Median, NL Average and AL Average to serve as a benchmark. All of these statistics are as of June 1, 2004. With any luck, this will lend less experienced baseball cappers a frame of reference for what the acronym means, why it is important and whether or not the number being analyzed is a sign of strength or weakness.

AVG - Batting Average.

The formula for Batting Average is simply Hits divided by At-Bats (Hits/At-bats). Note that a walk, hit by pitch or the seldom seen catcher's interference does not count as an official At-Bat. While batting average is probably the most widely used metric to evaluate a hitter, it can often be one of the most deceiving. It is similar to what we cited about ERA in our Pitching Acronyms article. That is, batting average can often be a byproduct of luck. How often have you seen a surefire Home Run be carried out of fair play by the wind or a missile line drive be swiped out of the air by a leaping shortstop. Similarly, how often have you seen a broken bat bloop single or a routine ground ball clearly mishandled by an infielder yet officially scored as a hit?

In addition, batting average does not take into account plate discipline (read: walks and strikeouts). Moreover, it often does not capture how important a hitter is to his team. For example, Alex Sanchez for the Detroit Tigers is hitting .354, while Albert Pujols is hitting a "mere" .317. Now … is there any question in regard to who the more valuable hitter is? And from a handicapping perspective, is there really a doubt as to which player will have a more significant impact on his team's chances of winning? Take nothing away from the speedster Sanchez (notwithstanding he has walked just 4 times in 189 At-bats and been caught stealing 10 out of 23 times). But he is no Pujols. You know it … and we know it. But those studying "just" batting average would not.

MLB Average: .266 Batting AVG

MLB Median: .267 Batting AVG

NL Average : .262 Batting AVG

AL Average: .271 Batting AVG

OBP - On-Base Percentage.

The formula for OBP is as follows:

(Hits + Walks + Hit By Pitch) / (At-bats + Walks + Hit By Pitch + Sacrifice Flies).

The formula looks scarier than it actually is. Basically, the numerator represents all the ways a batter can get on base. The denominator captures every plate appearance by a batter. OBP can prove more useful than batting average when assessing a hitter's value for several reasons. Recall that batting average doesn't count walks, hit by pitch or sacrifices; while OBP captures all of the ways a player can get on base. Would you rather have a guy with a strong batting average or one with a strong on base percentage? Two words for you… Barry Bonds.

This season Barry Bonds is leading the Major Leagues with an incredible .615 OBP. In layman's terms, Bonds reaches base 61.5% of the time. Note that the league wide OBP average is .336. Naturally, the higher the OBP, the better. Ready-made OBP calculations for players and teams are available all over the net, but here is Bonds' OBP formula for those that are interested.

(39 Hits + 72 Walks + 1 Hit By Pitch) / (109 At-bats + 72 Walks + 1 Hit By Pitch + 0 Sacrifice Flies) = .615 OBP.

For matters of perspective, here are the league wide average and median batting figures.

MLB Average: .336 OBP

MLB Median: .338 OBP

NL Average : .331 OBP

AL Average: .342 OBP

SLG - Slugging Percentage.

OBP is a solid metric because it picks up where batting average leaves off. Namely, and as we just noted, OBP captures all the ways a batter can reach base beyond just the old fashion hit. However, OBP has its shortcomings as well. The main issue with OBP (and batting average for that matter) is that it treats all hits the same. Specifically; a single, double, triple and home run are all weighted equally. This of course is a critical flaw. Is a player that has 20 singles, 10 doubles and 5 walks in 100 At-Bats equally valuable to a player that has 10 singles, 20 doubles and 5 walks in 100 At-Bats? Or how about a player with 5 singles, 20 doubles, 5 home-runs and 5 walks in his 100 At-Bats? Suffice to say, we'll take Mr. 5-20-5-5 over the first two players-every day of the week and twice on Sunday-even though his hypothetical batting average and OBP would be exactly the same (.350). Real simply, Slugging Percentage weighs hits according to relative importance… and that is of vast importance to a baseball capper!

The formula for Slugging Percentage is:

Total Bases / Total Number of At-Bats

Total Bases is calculated by awarding a player one total base for a single, two total bases for a double, three total bases for a triple and (you guessed it) 4 total bases for a home run. Slugging percentage thus becomes a pretty straightforward formula to calculate and like OBP is easily obtainable. But to solidify the understanding, let us return to Mr. Bonds and calculate his Slugging Percentage for the season. This year he has 18 singles, 7 doubles and 14 home runs in 109 At-Bats. Thus his Total Bases record is:

[(18 singles x 1) + (7 doubles x 2) + (0 triples x 3) + (14 home runs x 4)] = 88 Total Bases.

To calculate Bonds Slugging Percentage, simply take his total number of bases and divide by his total number of At-Bats. In other words: 88 Total Bases / 107 At-Bats = .807 SLG. And by the way, Bonds' SLG is best in the Major Leagues and almost twice the MLB average.

MLB Average: .422 SLG

MLB Median: .422 SLG

NL Average : .419 SLG

AL Average: .427 SLG

OPS - On Base Percentage + Slugging Percentage.

While Slugging Percentage fills the voids left over by OBP; like batting average it only rewards a player for hits generated (and not walks, HBP, etc.). Enter OPS. Perhaps our favorite capping metric of all, OPS captures both the rate at which a player gets on base (OBP) and the relative distribution (single, double, triple and home run) of that player's hits (SLG). In sum, OPS gives us the best of both worlds. To calculate OPS, simply add a player's OBP with his Slugging Percentage.

[(Hits + Walks + Hit By Pitch) / (At-bats + Walks + Hit By Pitch + Sacrifice Flies)] + (Total Bases / Total Number of At-Bats)

Barry Lamar Bonds, for example, has a .615 OBP and a .807 SLG. His OPS would therefore be a whopping .1422, which of course in tops in the Bigs.

MLB Average: .758 OPS

MLB Median: .758 OPS

NL Average : .750 OPS

AL Average: .769 OPS

So for evaluation purposes, the higher the AVG (batting average), the OBP (on base percentage), the SLG (Slugging Percentage) and OPS (On Base Percentage + Slugging Percentage); the better. That premise is simple. The more important concept is how each of the above metrics should be weighed in relation the other, as well as weighted in relation to the league averages. The above paragraphs objectively define each of the metrics and then offer a subjective evaluation of the metric's handicapping importance. The subjective, meaning, how it is interpreted from our office here in sunny Las Vegas.