It's a shame that two people can't play 3rd base at the same time, isnt it? But I do see your point, and, however reluctantly, I agree with you. As much as I like seeing Euclis out there, Mueller has been the 3rd baseman for longer, and he did win the AL batting title last year, and he is supposedly a defensive stud, and he has earned out respect.
This is the frustrating part, having to decide between two players who both have their pros, and whom you both like.