Runs created (RC) is a baseball statistic invented by Bill James to estimate the number of runs a hitter contributes to their team.
James explains in his book, The Bill James Historical Baseball Abstract, why he believes runs created is an essential thing to measure:With regard to an offensive player, the first key question is how many runs have resulted from what he has done with the bat and on the basepaths.
[1]Runs created attempts to answer this bedrock question.
The conceptual framework of the "runs created" stat is:
where OBP is on-base percentage, SLG is slugging average, AB is at-bats and TB is total bases, however OBP includes the hit-by-pitch while the previous RC formula does not.
This formula accounts for all basic, easily available offensive statistics.
where H is hits, BB is base on balls, CS is caught stealing, HBP is hit by pitch, GIDP is grounded into double play, TB is total bases, IBB is intentional base on balls, SH is sacrifice hit, SF is sacrifice fly, SB is stolen base, and AB is at bats.
Earlier versions of runs created overestimated the number of runs created by players with extremely high A and B factors (on-base and slugging), such as Babe Ruth, Ted Williams and Barry Bonds.
The 2002 version corrects this by placing the player in the context of his real-life team.
This 2002 version also takes into account performance in "clutch" situations.
The initial individual runs created estimate is then:
If situational hitting information is available, the following should be added to the above total:
where RISP is runners in scoring position, BA is batting average, HR is home run, and ROB is runners on base.
means "hits while runners are in scoring position."
The actual total of team runs scored is then divided by the estimated total team runs scored, yielding a ratio of real to estimated team runs scored.
The above individual runs created estimate is then multiplied by this ratio, to yield a runs created estimate for the individual.
Weighted runs created plus (wRC+) takes runs created and adjusts it to account for ballpark factors and the era a player played in.
This is usually expressed as runs created per some number of outs, e.g.
(27 being the number of outs per team in a standard 9-inning baseball game).
Runs created is believed to be an accurate measure of an individual's offensive contribution because when used on whole teams, the formula normally closely approximates how many runs the team actually scores.