Complex sentence: He was signed by Olympiacos C.F.P. to replace Yaya Touré, who departed for A.S. Monaco, but failed to break into the first team due to constant injury problems for the majority of his spell at the club.
Split into simpler sentences: He was signed from Olympiacos C.F.P. to replace Yaya Touré, who departed for A.S. Monaco, though he has yet failed to break into the first team due to constant injury problems. After joining Olympiacos C.F.P. he suffered from injuries for the majority of his spell at the club.