Marmol is coming off a terrible loss against the Netherlands which knocked the heavily favored Dominican Republic team out of the WBC. His manager Lou Piniella has already implied that how Marmol bounces back from that will say a lot about whether he has the right mentality to close. If it takes Marmol several outings to get his head on straight after the WBC debacle, there's a good chance Kevin Gregg will open the season as the closer.

As of right now, I'd still say Marmol is the slight favorite, but given the current cost of each player (Marmol is the 10th reliever off the board in Yahoo Leagues, while Gregg is the 40th), Gregg is the better gamble.