"The Pirates on Wednesday announced that at the team's request, Major League Baseball has placed Alvarez on the restricted list because Alvarez's agent, Scott Boras, informed the team that Alvarez would not sign the contract and wants it renegotiated."
UPDATE by Charlie: Dejan Kovacevic has more, including the full text of a statement from the Pirates, which points out that the commissioner's office received the agreement of another Boras client, Kansas City top pick Eric Hosmer, after Alvarez's, so Hosmer's contract could come into question if Boras continues to pursue this.
This is pretty unbelievable, even for Boras. My guess is that he will not get away with this, Alvarez will report soon, and then the Pirates won't have to make deals with Alvarez for six or seven years after that.
This article at MLB.com actually cites a source who says that Boras only wants another $200,000 for Alvarez, which would tie Alvarez with Buster Posey for the largest bonus paid in the draft. As far as I can tell--and I'm not a lawyer, so correct me in the comments if I'm wrong--this could jeopardize Alvarez's entire bonus. He's from a poor family, he just got $6 million, and he's letting his agent put all of it at risk (and also putting Hosmer's bonus at risk) for $200,000. If true, this is just amazing, and it's the sort of BS that will hopefully convince other talented amateurs to avoid Boras--it seems to be all about him, and not the needs of his clients. Alvarez has a Vanderbilt education, so it'd be shocking to me if he weren't smart enough to figure this out. If Alvarez is actually encouraging this, rather than foolishly trusting his agent to do the right thing, he's a spectacular jerk and it's going to be really hard to root for him.
By the way, there's no limit on the amount of time a team can keep a player on the restricted list. You better hope Boras wins the grievance, Pedro--the Pirates can wait forever, and you can't reenter the draft.