Editing Sabermetrics (section)

== Traditional measurements ==
Sabermetrics reflected a desire by a handful of baseball enthusiasts to expand their understanding of the game by revealing new insights that may have been hidden in its traditional statistics. Their early efforts ultimately evolved into evaluating players in every aspect of the game, including batting, pitching, baserunning, and fielding. 

=== Batting measurements ===
[[File:Ted Williams 1940 Play Ball.jpeg|thumb|right|[[Ted Williams]], the last MLB player to bat .400 for a season (in 1941)]]

A ballplayer's [[batting average]] (BA) (simply [[Hit (baseball)|hits]] divided by [[At bat|at-bats]]) was the historic measure of a player's offensive performance, enhanced by [[slugging average|slugging percentage]] (SA){{efn|name=powerhouse|Calculated by dividing [[total bases]] (the non-situational cumulative tally of all hits) by the total number of times at bat.}} which incorporated their ability to hit for power.  

Bill James, along with other early sabermetricians, was concerned that batting average did not incorporate other ways a batter can reach base besides a hit – as a batter on base can score runs, and runs, not hits, win ballgames.<ref name=":12">{{Cite book|last=Albert|first=Jim|title=Mathematics and Sports|publisher=MAA|others=Contributor : Mathematical Association of America|year=2010|isbn=9780883853498|editor-last=Joseph A. Gallian|pages=3–14|chapter=Sabermetrics: The Past, the Present, and the Future|volume=43|chapter-url=http://www.mathaware.org/mam/2010/essays/AlbertSabermetrics.pdf|jstor=10.4169/j.ctt6wpwsw.4}}</ref> 

Even though slugging percentage and an early form of [[on-base percentage]] (OBP) &ndash; which takes into accounts [[base on ball]]s ("walks") and [[Hit by pitch|hit-by-pitch]]es &ndash; date to at least 1941,<ref>{{cite news |url=https://www.newspapers.com/clip/117560636/the-powerhouse-column/ |title=The PowerHouse (column) |first=Jimmy |last=Powers |newspaper=[[New York Daily News|Daily News]] |location=New York City |page=45 |date=June 3, 1941 |accessdate=January 30, 2023 |via=newspapers.com}}</ref> pre-dating both Bill James (born 1949) and SABR (formed 1971),<ref name=":12" /> enhanced focus was put on the relationship of times on base and run scoring by early SABR-era baseball statistical pioneers. 

SA and OBP were combined to create the modern statistic [[on-base plus slugging]] (OPS). OPS is the sum of the on-base percentage and the slugging percentage. This modern statistic has become useful in comparing players and is a powerful method of predicting runs scored by any given player.<ref name=":022">{{cite web|url=http://baseball1.com/baseball-archive/sabermetrics/sabermetric-manifesto/|title=The Sabermetric Manifesto|last=Grabiner|first=David J.|work=The Baseball Archive}}</ref>  An enhanced version of OPS, "OPS+", incorporates OPS, historic statistics, ballpark considerations, and defensive position weightings to attempt to allow player performance from different eras to be compared.

Some other advanced metrics used to evaluate batting performance are [[weighted on-base average]], [[secondary average]], [[runs created]], and [[equivalent average]].

=== Pitching measurements ===
[[File:Ed Walsh portrait 1911.jpg|thumb|right|[[Ed Walsh]], whose career 1.82 ERA is the lowest in MLB history]]
The traditional measure of pitching performance is the [[earned run average]] (ERA). It is calculated as [[earned run]]s allowed per nine innings. Earned run average does not separate the ability of the pitcher from the abilities of the fielders that he plays with.<ref name=":5">{{Cite web|url=http://www.baseballprospectus.com/article.php?articleid=878|title=Pitching and Defense: How Much Control Do Hurlers Have?|last=McCracken|first=Voros|date=January 23, 2001|website=Baseball Prospectus}}</ref> Another classic measure for pitching is a pitcher's [[winning percentage]]. Winning percentage is calculated by dividing wins by the total number of decisions (wins plus losses). Winning percentage is also heavily dependent on the pitcher's team, particularly on the number of runs it scores.

Sabermetricians have attempted to find different measures of pitching performance that exclude the performances of the fielders involved. One of the earliest developed, and one of the most popular in use, is [[walks plus hits per inning pitched]] (WHIP), which while not completely defense-independent, tends to indicate how many times a pitcher is likely to put a player on base (either via walk, hit-by-pitch, or base hit) and thus how effective batters are against a particular pitcher in reaching base.

A later development was the creation of [[defense independent pitching statistics]] (DIPS) system. [[Voros McCracken]] has been credited with the development of this system in 1999.<ref>{{Cite journal|last1=Basco|first1=Dan|last2=Davies|first2=Michael|date=Fall 2010|title=The Many Flavors of DIPS: A History and an Overview|journal=Baseball Research Journal|volume=32|issue=2}}</ref> Through his research, McCracken was able to show that there is little to no difference between pitchers in the number of hits they allow on balls put into play &ndash; regardless of their skill level.<ref name=":4">{{Cite web|url=http://www.beyondtheboxscore.com/2014/1/17/5309808/how-has-sabermetrics-changed-baseball|title=How has sabermetrics changed baseball?|last=Ball|first=Andrew|date=January 17, 2014|website=Beyond the Box Score}}</ref> Some examples of these statistics are [[Defense-Independent ERA|defense-independent ERA]], fielding independent pitching, and [[Defense-Independent Component ERA|defense-independent component ERA]]. Other sabermetricians have furthered the work in DIPS, such as [[Tom Tango]] who runs the ''Tango on Baseball'' sabermetrics website.

''[[Baseball Prospectus]]'' created another statistics called the [[peripheral ERA]]. This measure of a pitcher's performance takes hits, walks, home runs allowed, and strikeouts while adjusting for ballpark factors.<ref name=":5" /> Each ballpark has different dimensions when it comes to the outfield wall so a pitcher should not be measured the same for each of these parks.<ref name=":62">{{Cite book|title=The Sabermetric Revolution: Assessing the Growth of Analytics in Baseball|last1=Baumer|first1=Benjamin|last2=Zimbalist|first2=Andrew|publisher=University of Pennsylvania Press|year=2014|author-link=Ben Baumer}}</ref>

[[Batting average on balls in play]] (BABIP) is another useful measurement for determining pitchers' performance.<ref name=":4" /> When a pitcher has a high BABIP, they will often show improvements in the following season, while a pitcher with low BABIP will often show a decline in the following season.<ref name=":4" /> This is based on the statistical concept of [[regression to the mean]]. Others have created various means of attempting to [[Pitch quantification|quantify individual pitches]] based on characteristics of the pitch, as opposed to runs earned or balls hit.