If both Mathieu and Mascherano leave, this could be a very important signing. We would need experience for a role/position on the team that is hard to find in the market, especially the Spanish. Martinez fits the style of play. Him as LCB backup, Marlon the RCB. Davinson Sanchez also a good option, but he's also young like Marlon. Situation could become unreliable at the back if injuries start to occur or if we want to try a 3-man defense. From what I've heard, Martinez has played nicely under a Barca-style of play under Eusebio, which is a good sign.