I think the above may qualify as a whine; I'm not sure. :p

Anyway, here's the explanation:

First of all, how are the IP/OUTS and ERs allowed comparable?

Carpenter pitched 7 innings and Rodney only 2.

Carpenter allowed 1 earned run and Rodney allowed 2.

More than three times as many IPs for Carpenter, half as many ERs allowed.

Most importantly, though, you left out the -6 for the save opportunity (which was not offset by the +8 for the save), so the -13 includes that 6 points, and if you want to compare it exactly with Carpenter, figure it as a -7.

I've already said that I think that a flaw in the scoring system is that it penalizes a RP twice in these situations: -6 for the loss and -6 for the blown save (see my chart above).

I think that a pitcher - a "closer", who is theoretically the top guy on his team at that job, not a #4 or #5 starter, for example - who comes into a game with a lead to protect, in a game where his team has kinda mentally put the game into the win column already, who proceeds to turn the win into a loss has done a lot more damage to his team than when a #5 starter loses the game (I know, a loss is a loss, but stil.....).

But that said, I do think -as the chart shows - that the negative score in those cases is a little disproportionate in relation to the act, and I'd likr to figure out a way to adjust it for next season so that the guy is not charged a -12 because he had a blown save and a loss.