I’m pleased to announce that FanGraphs is now carrying a comprehensive base running stat: Mitchel Lichtman’s Ultimate Base Running (UBR).
UBR is now being included in WAR for years where UBR is available (2002-2011).
Though 95% of all players will have their WAR changed less than .4 wins in any particular season and less than 1.3 wins over their careers, we feel that the inclusion of UBR in WAR will help properly credit/debit players who truly excel or are particularly awful on the base paths.
Here’s an excerpt from the UBR primer that we’ll be posting later today:
Base running linear weights or base running runs, or Ultimate Base Running (UBR), is similar to the outfield arm portion of UZR. Whatever credit (positive or negative) is given to an outfielder based on a runner hold, advance, or kill on a batted ball is also given in reverse to the runner (or runners). There are some plays that a runner is given credit (again plus or minus) for that do not involve an outfielder, such as being safe or out going from first to second on a ground ball to the infield, or advancing, remaining, or being thrown out going from second to third on a ground ball to SS or 3B.
Runs are awarded to base runners in the same way they are rewarded to outfielders on “arm” plays. The average run value in terms of the base/out state is subtracted from the actual run value (also in terms of the resultant base/out state) on a particular play where a base runner is involved. The result of the subtraction is the run value awarded to the base runner on that play.