If it's just to cover a gap while Crisp mends, then why isn't it Murphy riding the Pawtuckett shuttle? Sure, he just got sent down, but with Piniero going on the DL for Jacoby to come up, it could have been Murphy. And Murphy has done everything he needs to be an injury stop-gap. No this smells like something bigger.
I think it's possible that they've come close to terms on a deal for Crisp, and now they are trying out the replacement.