honestly if you want to trade a sp away, i'd try to upgrade at 3b before trying to get a closer. since i'm fairly new i can't give you specific trade scenarios, but out of your starters, i'd probably shop around ubaldo and billingsley to teams who are weak in pitching and get a feel for who's available. felix/price are enough to lock down the top of your rotation and you'd be selling low on greinke because of his injury.
for closers, you can probably just browse the ww. if bailey's out for oakland, you can grab fuentes. or rauch in toronto. or whoever wins the job in texas if feliz becomes a starter.viewtopic.php?f=29&t=424091