I think too many people look at this trade and look at Pena as Arroyo's immediate replacement, comparing the two of them on too similar ground. Pena was NOT brought here to fill Arroyo's shoes, obviously. They are two completely different players and both gave/give to this team in different ways. Arroyo gave a quality start once every five games, but Pena has the potential to give you his bat every game (and in doing so, give you 45-50 homers a year). DiNardo looked fine out there today against the M's, and seeing that was a relief for me. I'd much rather have DiNardo out there than Wells, and if DiNardo keeps this up we won't miss Arroyo too much. That's not to say I won't miss him completely, but if someone can fill his role, then all is good.
Seeing Wily Mo get better and better this year and next will be much more worth it than keeping Arroyo in this rotation when DiNardo can fill his role. I know it was only 1 start, but it was a good one nonetheless, and he will only get more comfortable there. I think he'll do fine as a 5th starter.