The Kansas City Star has an excellent article by Joe Posnanski about why the Royals would deal for Milton Bradley. He suggested three reasons. The first reason is the good relationship Buddy Bell had with Bradley from their days together with the Indians. The second is the ability to flip Bradley to a contender in the next five weeks or receive a draft pick when he leaves as a free agent at season's end. The last reason is as a motivational tool for his last place ball club.
Of the three, I find the second one most plausible. On the first, Buddy Bell has done absolutely nothing to make anyone other than Dayton Moore believe his opinion should matter at all. So he can judge the character of a player who has forced his way off every team he has ever been on? And that judgment is a positive one?
As for the third, exactly how is a last place team motivated by acquiring yet another OF who will block the development of a younger player like Joey Gathright or Billy Butler? What I see as likely to occur are those players learning they will not get a chance at all and becoming demoralized and inured to losing ways.
The second reason is the best. All that Dayton Moore needs to do it net more than Leo Nunez plus the amount of money the Royals would have incurred until Bradley was dealt. With 14 weeks remaining, this could have been as high as 5 weeks or $800,00 or so. Seems a somewhat risky proposition given Billy Beane was willing to accept Leo Nunez after Beane had already made efforts to gauge MB's market value.
If Moore was unable to best that price, then the team would still get a draft pick for losing Bradley in free agency. However, I'd ask whether that player is worth the $2MM in salary the Royals also agreed to pick-up in the Bradley trade and the bonus the Royals would have to pay for that draft pick to sign.