Cubs Trade for Randolph

Today the Cubs took a step to improve their bullpen. They acquired left-handed reliever Stephen Randolph from the Diamondbacks for a player-to-be-named-later. This is not a bad trade for the Cubs as it doesn't really cost them much as the PTBNL is probably not going to be much more than a midlevel prospect at best. By no means I am saying that this is a good trade either. The Cubs pitching coach will have his work cutout for him in Randolph as the major knock on him is that he has a hard time throwing the ball over the plate. Last season in 81.2 IP's he walked 76 men. If he can improve his control then he will be an improvement over Mercker, but with the showing Ohman put on in Winter League, this move mystifies me. I am not sure if Randolph is here for insurance for Remlinger getting hurt, Ohman failing to get out big league hitters or the Cubs just feel that they need 3 lefties in the pen.