It'll probably be a long time until we see another scenario like the Boston Red Sox last September. There were rumors they were going to trade for Bruce Chen on the last day of the season. I've read or typed that 68 times, and it never stops being amazing.
To prevent that from happening this season, the Red Sox signed a few noteworthy pitchers to minor-league deals, including Aaron Cook. But with the noteworthiness comes a little contract leverage, and Cook now has options now that the Red Sox did not call him up by May 1. From WEEI.com:
Cook has 24 hours to either exercise his opt-out clause or work out an agreement to stay in the Sox organization. If he exercises the opt-out clause, the team would then have 48 hours to call him up or trade him. At the end of that window, if he was not in the majors, then the 33-year-old would become a free-agent.
It's possible that the Red Sox and Cook will work out a new contract, but it's also possible that the Red Sox trade him. What, like a bunch of pitchers will get hurt, making them regret the trade? Yeah, right. What are the odds of that?
(When you put it like that, you'd have to think the Red Sox work something out. Remember: Bruce Chen.)