I wonder why? Greinke almost certainly would put them in the playoffs and a contender to win it all again.
Probably because pitchers' arms don't seem to last that long anymore. Also, for some reason, the Giants have a hard time keeping their pitchers' ERA's low for an extended time unlike Atlanta in the 90's who had the same pitchers/rotation pitching great year after year.
Seems like it would have been worth it.
A baseball geek might say he was worth it, using WAR.
A win-above-replacement is worth $8 mil, so Greinke’s WAR of 4 or so would be worth his $30+ million annual salary.