Tuesday, April 05, 2005

ERV Scoring, Game 1

As we may or may not have promised a while ago, Nats Blog will be (hopefully) ERV scoring each Nats game this year. If you remember, ERV scoring is based on the principle of judging a plate appearance based upon the change in the expected value (in runs) of the situation before and after the hitter's plate. Thus, if the Nats would expect to score 2 runs with bases loaded an nobody out, a grand slam would have the value of: 4 runs- 2 expected runs + expected value of nobody on nobody out = ERV of plate appearance. Remember, we are using the end-of-2004 ERV values provided by Baseball Prospectus, which will have to be adjusted (retroactively) at the end of the 2005 season. The numbers won't move terribly much, however.

Anyway, I assure you it's all very scientific.

Here's the log I put together:

Player PA 1 PA 2 PA 3 PA 4 PA 5
Wilkerson 0.388 -0.2513 -0.3036 -0.5219 -0.3036
Guzman -0.3763 -0.1731 0.2145 -0.2513 -0.246
Vidro -0.3036 -0.1135 -0.4605 0.263 -0.2513
Guillen -0.246 -0.2513 -0.2513 0.4081 -0.1731
Johnson 0.388 0.263 -0.1731 0.6369 -0.1135
Castilla -0.3408 -0.3036 0.1325 1
Sledge 0.1413 -0.246 1.8675 -1.5946
Schneider 0.2224 -0.2513 0.1325 0.388
Hernandez -0.3359 0.263
JJ Davis 0.2759
Blanco -0.3763

A couple of notes: Castilla getting a hit and then getting thrown out at second base while Johnson went to third was a net negative for the Nats the way I scored it. Although he, in the abstract, turned a man-on-first, no-one-out situation (.9259 runs) into a man-on-third, one-out situation (.9722 runs), in reality, his attempt to get to second base turned a man-on-first, man-on-second situation (after his hit) into a man-on-third, one-out situation, a net negative. Sorry, that's what the numbers say.

In addition, note Terrmel Sledge's two-out, two-run home run in the 6th: +1.8765 runs! However, the T-man giveth, the T-man taketh away. His double play ball with the bases loaded later in the game was almost as bad as his home run was good: -1.5946 runs. Sledge was still positive on the day, but that double-play ball really hurt (as anyone watching the game would note as well).


At 3:38 PM, Blogger DM said...

I would score Castilla's being thrown out a little differently, by separating out his "Batting" and "Running" RV. First, if he stays at first, he has improved the Nats ERV from 0.93 (1st, no outs) to 1.85 (1st & 3d, no outs) or +.92 RV. However, by trying to get to second, he turned a 1.85 into a 0.97 (3d, one out), so as a baserunner, he gets a -.88 RV. So, the bottom line for Castilla is:

Batting RV: +0.92
Running RV: -0.88

Thus, I have the whole play as a slight positive for the Nats (0.04).

If he had made it to second, the Nats ERV would have gone from 1.85 to 2.13, for a Running RV of +0.28 for Castilla. That shows that trying for the base was not a good risk, especially for a sloth like Vinny.

I also scored his nice play on the bunt that Johnson bobbled as saving the Nats 0.9 runs. So, overall, Vinny was a good contributor to the Nats yesterday, despite the baserunning.

At 9:38 AM, Blogger Chris Needham said...

I don't know how errors factor into the system, but on the Castilla play, Johnson took third, on the bobble by the left fielder.

If you take the error out, the play was nothing more than a sac bunt, essentially.

At 1:46 PM, Blogger DM said...

You're right Chris. I forgot about the error. You factor that in by giving Castilla credit only for making it 1st and 2nd. Assign the value of getting to 1st and 3rd to the error. Then the value of going to 3d and one out to Castilla's running. So here's the final tally:

Castilla Batting: +0.53
Burrell Fielding: +0.39
Castilla Running: -0.88

So Castilla's RV total for the play is -0.35, which is equal to a sac bunt as you say, and helps explain why the sac bunt is a bad play, unless you are sure the batter will strike out.


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