There's a primer posted, and here's a brief summary from it --
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.
Worst Giants by UBR:
| Bengie Molina | -17.0 |
| Barry Bonds | -15.8 |
| Pedro Feliz | -6.9 |
| J.T. Snow | -4.7 |
| Moises Alou | -3.7 |
And the best...
| Fred Lewis | 10.4 |
| Ray Durham | 8.7 |
| Randy Winn | 8.1 |
| Emmanuel Burriss | 6.4 |
| Andres Torres | 6.1 |
I'm a little surprised that Nate Schierholtz didn't crack the top five, and that Burriss did.
Anyway, this is a useful stat -- much more so than the four-component speed score that used to be Fangraphs' only baserunning/speed metric. I'm not sure that it's better than equivalent baserunning runs, but there's a good comparison between the two posted over at Beyond the Box Score. Note that UBR does not include SB/CS.
As for the current team UBR leaders, Aubrey Huff is already at -1.0 whereas Aaron Rowand leads the team at 2.2; as always, small sample size caution should be applied. Pat Burrell currently ranks third on the team at 0.6...
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