I'll quote part of a paragraph, but it's worth your read:
Sometimes, for players who are borderline roster considerations, you may be safer by leaving him OFF the 40-man. However, if for some reason (add a free agent, add someone through trade, need someone during the season due to injury) you need to add a player to the 40-man at a later date, you may be forced to outright someone to make room. When you outright a first year roster player, he still has all of his minor league options, so teams can claim him and send him right into their minor league system.
I think this applies to Eduardo Morlan. Although, Morlan could become the Pirates mop-up man just as easily as he could be offered back from the Indians in May, so who knows what the future holds for him.