What are you basing this on? It seems wrong both in terms of the size of the handicap and the strength of Ishida.
Ishida first: while he is certainly not top 100 in the world anymore, he is quite probably top 1000 (there are something like 1500 professionals out there, and he is probably above average for Japanese professionals, maybe above average for all the countries (see https://www.google.com/search?q=yoshio+site%3Ahttp%3A%2F%2Fi...). So he's closer to a grandmaster than a master. And in any case, other professionals have lost at four stones (see http://www.computer-go.info/h-c/index.html).
Second, regarding the handicap: I am not knowledge enough about chess to say, but it sounds high. In Go, I have beaten players who officially should give me three stones (though as you approach professional strength, it is true that players would be better at preserving that advantage and converting it into a win). I'd estimate the handicap as somewhere between 400 and 600 GoR points (which are similar in spirit to ELO ratings--http://senseis.xmp.net/?EGFRatingSystem). It is worth noting that the best European players take two to three stones from strong Asian professionals.
Ishida first: while he is certainly not top 100 in the world anymore, he is quite probably top 1000 (there are something like 1500 professionals out there, and he is probably above average for Japanese professionals, maybe above average for all the countries (see https://www.google.com/search?q=yoshio+site%3Ahttp%3A%2F%2Fi...). So he's closer to a grandmaster than a master. And in any case, other professionals have lost at four stones (see http://www.computer-go.info/h-c/index.html).
Second, regarding the handicap: I am not knowledge enough about chess to say, but it sounds high. In Go, I have beaten players who officially should give me three stones (though as you approach professional strength, it is true that players would be better at preserving that advantage and converting it into a win). I'd estimate the handicap as somewhere between 400 and 600 GoR points (which are similar in spirit to ELO ratings--http://senseis.xmp.net/?EGFRatingSystem). It is worth noting that the best European players take two to three stones from strong Asian professionals.