Why did the royals trade Zack Greinke?

The Kansas City Royals traded Zack Greinke to the Milwaukee Brewers in December 2010 primarily to bolster their farm system. At the time, the Royals were in a rebuilding phase and aimed to acquire young, promising talent in exchange for their ace pitcher. The trade netted them several prospects, including shortstop Alcides Escobar and pitcher Jake Odorizzi, which aligned with their long-term strategy to develop a competitive team.