This is by Dave Cameron at ESPN. It is an insider, which I usually don't post, but this is part of a larger article and seems harmless enough.
"The Rays have turned themselves into a winning organization by finding value in players that aren't as well appreciated as they should be, and Crisp is perhaps the most underrated free agent on the market this winter. During the last three years, he's averaged 3.7 WAR per 600 plate appearances, putting him nearly on par with Carlos Beltran, who will command significantly more money than Crisp. Injury concerns with Crisp are legitimate, and while he might not be an ironman, he's quite productive when he's on the field.
Bringing Crisp in to take over center field gives the team the ability to trade B.J. Upton, who is due another raise in arbitration and is just a year away from free agency. Crisp will likely get a lower salary as a free agent than Upton would in arbitration, so the team could actually save money and use Upton to improve other parts of the roster.
Given his pedigree and athletic ability, there will be a market for Upton's services, and the Rays would almost certainly get more overall value from Crisp in center, the talent Upton would bring back in a trade, and the influx of cash."