Let's say that some team is stupid enough to pay him 100M. Even so, by staying with the Red Sox an extra year, Ellsbury could possibly double that 100M over the course of his career.
If Ellsbury takes the two years here, re-establishes value, he'll make 20 million in 2014, and then pull in a significantly larger contract at around 150-180 million for the rest of his career-- well beyond the 100 million he would otherwise make in 2014.
Teams WILL give Ellsbury the annual value in 2014, but the length of contract is going to be the concern. 4-5 years is going to be the max anyone gives, and sure, maybe 5/20 is a possibility, but then what? He'll be a 35 year old, and his most consistent tool-- speed-- will be fading, who probably turned into a horrible contract the first time around. There are no absolutely no guarantees that he'll get another big contract at the end of 2018. There is also the matter that he will get a guarantee on 2014 if he has a poor 2013.