There was an article discussing this up at Fangraphs the other day: http://www.fangraphs.com/blogs/the-myth-of-six-years-of-team-control/ If the players union could somehow prove the team acted in bad faith by reassigning Springer to the minors in retaliation for refusing the contract, they would certainly have a valid reason to file a grievance. They won't be able to make that case though, because as people already mentioned, he hasn't done anything that would convince a neutral arbitrator that the team isn't sending him down for performance reasons. A rebuilding team with limited resources like the Astros has every incentive to buy up the arbitration years of its most talented players as a cost-control measure, and in cases where players aren't interested, has an equal incentive to leave those players in the minors to develop as much as possible before starting the service clock. That's not the team "screwing over" the players, it's the team acting in its best interest within the current rules of the CBA, and it certainly doesn't make them a "stupid franchise," it makes them a smart one. Did I mention how absolutely stacked with statistically-savvy, sabermetric types the Astros front office is? Maybe the Twins should try that.