The save stat was not a bad idea in principle. But the rules are messed up.
It still amazes me that Rivera got charged with a 'blown save' in Game 5 of the 2004 ALCS. He came in in the 8th with runners at first and third, no outs and a one run lead. He gave up a sac fly that tied the game. He went on to pitch 2 innings and be charged with 0 runs, yet he got the 'blown save'. Tom Gordon, who put those runners on in the 8th, got credited with a hold and no blown anything.
If the rules are no good, the stat isn't much good.