Right or you could get absolutely nothing out of Matsuzaka. At least with Pierre you can look back at his carrer ... in MLB ... not some minor league ... and you know what you might get. Yes maybe you overpaid, but you know that unless something drastic happens you're going to get that kind of production. The Sox have no idea what Matsuaka could possibly do in MLB. You can say what you want about his numbers in Japan, but you have no idea what he is capable of in MLB.
I'd much rather spend 45 million for 5 years of a sure thing, than 51 million for a cup of coffee with an unknown.