OBP, OPS, SLG - QMIND-Team/Sabermetrics GitHub Wiki

# What are OBP, OPS, and SLG

OBP

On-Base Percentage

OBP measures how frequently the batter reaches base. It considers hits, walks, at-bats, sacrifice flies, and hits by pitches. Errors by fielders are not accounted for in OBP. It is given by,

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

The numerator is also called the Times-on-Base (TOB). Batters with high OBP play at the top of the batting line-up. Compared to BA (batting average: no. of hits / at-bats), OBP encompasses a lot more factors. Batting average does not consider walks and hits by pitches. Batting average also does not differentiate between say a home-run and a single. An improvement to OBP is OBP+ which accounts for the league that the player is from and where the game is played.

SLG

Slugging Percentage/Average

SLG is the total number of bases divided by the number of at-bats. It aims to measure the power of a hitter. i.e. SLG= TB/AB=(1B+(2×2B)+(3×3B))/AB

SLG accounts not only for hits but also gives them a multiplier. Doubles are worth more than a single, etc. But the limitation is that we cannot say that doubles are exactly twice as much important than singles.

OPS

On-base Plus Slugging

OPS is the sum of OBP and SLG. It aims to measure the ability of a hitter to reach base and deliver powerful hits. OPS=OBP+SLG OPS weighs OBP and SLG equally even though OBP plays a larger role in the number of runs scored by a hitter. OPS+ is adjusted OPS which accounts for the ballpark and the league. wOBA (weighted on-base average) solves the issue of inaccurate importance given to singles, doubles, and triples by using a more precise weightage of each offensive outcome.

Batting Average Fields in Play (BABIP)

Batting Average Fields in Play (BABIP)

Formula: (H-HR)/(AB-K-HR+SF) Methodology: Batting average excluding homeruns and strikeouts while counting sacrifice flies as outs. BABIP is essentially the batting average for when the ball is hit into play. Purpose: To measure the batting average for only balls that are impacted by the defence Acronyms Hits (H): The hitter must reach first base, or any following base after hitting the ball. Home runs (HR): The batter hits the ball out of the field which allows all of the offensive players on the field to automatically score. At bat (AB): When a batter is placed against a pitcher. A batter would not receive credit for an AB if his plate appearance ends in one of the following circumstances.

  1. The pitcher throws outside of the strike zone four times in a row which causes a “walk”
  2. The player is hit by the pitcher
  3. Performs a sacrifice fly
  4. Awarded first base due to interference
  5. Is replaced by another hitter before his bat is completed Strikeouts (K): Occurs when a batter accumulates 3 failed swings at an AB which then terminates the AB attempt Sacrifice Fly (SF): When the batter hits the ball into the outfield to be caught but gives time for another other offensive players to score. Factors that affect BIPIP: Luck: The BIBIP of players tends to fluctuate around their mean A Pitcher’s Defence: A good defence is more likely to cause outs, which would decrease the BABIP of a pitcher. Talent of Batter: Batters who are fast and have high accuracy tend to have a higher BABIP How can this be useful? • Since pitchers have little control where the ball goes after it is in play and the strength of their defence, their BABIP is mostly out of their control. A pitcher with a high BABIP would presumably perform better in the future or on a stronger team. • BABIP takes a long time to stabilize, so if a new batter has high offensive numbers and a high BABIP, then the success of the player may be partially be due to luck.

References

https://en.wikipedia.org/wiki/On-base_percentage https://www.baseball-reference.com/bullpen/On_base_percentage https://www.wikihow.com/Calculate-On-Base-Percentage http://m.mlb.com/glossary/standard-stats/on-base-percentage http://tangotiger.net/wiki_archive/On-Base_Percentage_(OBP).html http://m.mlb.com/glossary/standard-stats/on-base-plus-slugging https://en.wikipedia.org/wiki/On-base_plus_slugging http://tangotiger.net/wiki_archive/Slugging_percentage.html http://m.mlb.com/glossary/standard-stats/slugging-percentage https://en.wikipedia.org/wiki/Slugging_percentage https://www.baseball-reference.com/bullpen/Slugging_percentage https://www.blessyouboys.com/2011/12/13/2630655/making-sense-of-on-base-percentage-slugging-percentage-ops-and https://www.beyondtheboxscore.com/2014/5/26/5743956/sabermetrics-stats-offense-learn-sabermetrics