yeah, in a keeper league this trade doesn't happen.... but in a non-keeper league you're getting stanton AND ryu for locke? do it all day every day and twice on sundays. locke is no guarantee to keep up his magical mystery season and seeing as you obviously nabbed him for nothing from the FA/WW list, you're essentially giving up nothing to get stanton, who still should be a ~.270/30/100 pace player for the rest of his at bats this year. don't let the whole marlins thing faze you.... stanton is steak over sizzle, as he was ~37HR/86RBI last year despite missing a whole month.
obviously since the marlins are going nowhere this year you do run the risk that if he gets a little dinged up they'll be super mega cautious with him and err in favor of missing time, but like, at his core he's arguably one of the top ~3-5 raw power hitters in the game right now, so i think you give up whatever brilliance locke has been giving you and cash in for a more proven young star like stanton. no doubt.
and take a look @ my thread when you get a chance, will ye!?!?!? viewtopic.php?f=26&t=463326