How are the Reds worse for this move?
I believe Mo Pena brought a lot of balance to the lineup. Pitchers at least have to respect his ability to put one "out" at any time. I just do not think that they can replace that with anyone on the roster or anyone in the system.
This team had better figure out that the young talent that virtually comes up through the sytsem, is the talent that you want to keep around. How many teams out there trade this type of player? Eventually this trade will come down to what we get out of Arroyo, chances are after a season or a season and a half at the GAB it will be considerably less than a Mo Pena.