Boldin didn't trust Beane. Here is a transcript of a possible conversation that may have occurred, possibly
Boldin: Why did you trade Sammy?
Beane: Wanted the draft picks.
Boldin: How does this trade make the team better today?
Beane: It doesn't, I am building for the future.
Boldin: Dude I am 38. With Sammy we could win now. There is no "future" for me, without Sammy on this squad this team has minimal ability to win this year. You told me you wanted to win when I signed.
Beane: Well you screwed up, you trusted me. BTW, I am telling everyone that having you on the team made this trade possible.
Boldin: Kiss my ..., I quit.
Beane: At least we get Kaelin Clay to cover losing Watkins and Boldin.