Not really true, he must do something right to make the stars in a team. You can look at Solskgaer in Man utd. Do you make managing a whole team of stars easily? Yes, Martinez has terrible denfence record and I dont think he improves a lot but please judges him fairly.
During his managing time, he doesnt have that money to replace Distin, Jagelka, Hetinga…He only can choose to promote stones and sign a free transfer Alcarez and about 12m Funes Mori. Does we really give him the money to build up the defense?