@mshaune
It's an interesting approach but unfortunately it's too flawed to be of any use, for the reasons already given.
If tennis player 'A' beats player 'B' but loses to player 'C', what if anything can you infer?
I agree that Karpov seems to have had some problems with certain match play situations, but these seem to be limited to those occasions when he was ahead and only needed draws to win the match: he was crushing Korchnoi in '78 (3 ahead with only 5 to play) and almost blew it; and needing only a draw in the last game against Kasparov to become champion in '87, he lost (against 1.Nf3 of all openings, if my memory serves me right). This flaw aside, I'd say he was very strong in match play.
In terms of match play only, I think it's quite possible that the wily old Korchnoi would have been not far off his prime in '78. GM's deteriorate with age at very different rates (cf Karpov and Smyslov), and what he'd lost in sharpness he may well have made up for in experience and the art of psychology. Don't forget that Karpov had the weight and expectation of the Soviet authorities "behind" him, with all the pressure that implies.
Chess results are far too situational to be boiled down to numbers, so I agree with dannyhume that the opinions of GMs who played both Fischer and Kasparov would be more instructive.
1. I am not pro-Kasparov, I just think he is better
2. If this remains just a debate and not a personal war, I think it will be okay.
3. Let's look at a survey I have made (I have voted in it, but there are ten votes in total), with the top ten best players ever. First gets ten, second gets nine, etc., for each vote (The scores are from chessgames.com).
Kasparov 99 (candidate)
Capablanca 71 (candidate)
Karpov 64 -vs. Kasparov: 25W, 39L, 137D
Fischer 63 (candidate)
Morphy 45- never played any of the candidates
Lasker 38- vs. Capablanca: 2W, 6L, 16D
Alekhine 25- vs. Capablanca: 7W, 10L, 33D
Steinitz 16- never played any of the candidates
Tal 14- vs. Fischer: 4W, 4L, 5D
Anand 13- vs. Kasparov: 8W, 26L, 43D
You be the judge.