ok as an avid follower of argentina let me comment on otamendi in his early days he was considered an incredible one on one defender who was extermely error prone.
his defending style is compared to ayala, agressive and proactive was similar to kompany also.
but in the last year or so something changed, his positional sense and distribution improved remarkably. he became one of the or if not the best defender in la liga.
imagine kompany mixed with Demichelis thats how good he became presumably because of playing in the tactical la liga and then he was called up for the copa america and was argentina's best defender.
in short he would be a incredible addition.