The agent for Jake Odorizzi confirmed a deal is in place for Zack Greinke that includes the minor league pitcher. Some of the players reported in the trade are not confirmed yet:

The Royals will receive Odorizzi, shortstop Alcides Escobar, outfielder Lorenzo Cain and another player from the Brewers. Cain’s agent, Joshua Kusnick, confirmed on his Twitter account that his client is going to Kansas City and indicated that another client, minor league pitcher Jeremy Jeffress, could become the additional player.

I missed the inclusion of Cain earlier. He hasn’t played that much over the last two seasons due to a knee injury. He did steal 26 bases in 29 attempts in the minors in 2010, so I would guess the knee is okay. He just makes the Royals haul better.

Update: Multiple sources are reporting that Jeffress is indeed the fourth player in the deal.