According to the rules, Cain was not eligible for the win, and neither was Walker. Since Cain only got a no decision, that isn’t really a negative. A closer is never judged by wins, only saves/blown saves, so Wilson gets his penance. Walker never deserved the win. And because offense is out of the pitcher’s hands, most agree that ERA is the only meaningful pitcher stat, and that is okay for Cain in this scenario. So I don’t disagree with the scoring.

If judgment is introduced in these things, then I give you the following scenario which I think is even more lopsided:

Cain pitches 3 innings, gives up 1 run, leaves with the bases loaded, no outs in 4th, Walker gets 3 outs, no runs score. Cain is pitcher of record, gave up 1 run. Giants haven’t scored.

(Mets 1, Giants 0)

Walker finishes the rest of the game, and gives up 9 runs. Meanwhile Giants also score 9 runs, but never tie or lead the game.

Final: Mets 10, Giants 9.
Losing pitcher Cain. 3 ERA.
Walker gets no decision with 13 ERA.

Give up 1 run in 3 innings, lose.
Give up 9 runs in 6 innings, nd.

The only reason this happens is the timing of the Giants scoring their runs, which is out of the pitchers’ control. Either one concurs with “pitcher of record” mentality or not.

Note that I’m not disagreeing with your frustration about the apparent injustice.

Great 2-part column in today’s Chronicle by Bruce Jenkins about the degeneration of pitching:
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/08/26/SPJV122RBS.DTL