Yes, Abidal is best at CB, but played for us mostly at LB and was a great success. Point being the you can flourish for a team without ideal position. I don't see how Martinez's passing is wasted in our system. Pique has such a huge influence on the ball and is as important as the midfield for how we operate.
I don't see how your argument is helped by saying Martinez has been more impressive at Bayern than Athletic; Bayern are a huge team with great players.....
Forget about having Martinez's best interests at heart. What do we need in a player? What our management though we got in Song last year. Someone who can play in the Busquets role and at CB. Well, we didn't go for Martinez as he was too expensive. It does not matter if his influence in attack is reduced. He would be perfect for us. Great on the ball; strong and fast; great in the air; plenty of experience at CB and DM; Spanish.
Perfect signing. Stupid error.
You keep attributing Athletic's success last season to Martinez playing at CB and saying he was colossal for them there, but he's been even more colossal and impressive at Bayern having the same influence. It's a flawed comparison but not more flawed than you saying that they got to 2 finals because of Martinez being used at CB.
Martinez is wasted because he organizes the midfield into a defensive unit that covers the back line and greatly helps stop attacks at their roots and neutralizes creative players, at CB he'd just be making the final tackles which is a waste of his abilities when positioned in front of the defense. Plus while Pique does have influence in passing he is far from as influential as Martinez in the DM role because he links up and provides a base for players like Schweinsteiger and Ribery to push forward. Playing at CB he'd just be reduced to being a false sweeper that tries a bunch of hollywood long balls without much success.
Having his interests at heart is better than simply making him a pawn to fit our system. Getting a CB who can play as backup DM is better because
a) his primary attributes are used in his primary position
b) if needed he can fill in to the DM role as backup.
That way he gets his profile accounted for and gets the time he wants in the position he wants and can flourish at his best as opposed to being a DM forced to play CB and getting the occasional game in their native position.