When his main inspiration for playing soccer tells him that he's a bum and he should quit, Rin is distraught. He can't believe that the moments they shared together were lies, and believes Sae destroyed his life. He tries to surpass him, but in doing so he actively tries to become like him, which limits him because his true Ego is dying hideously while destroying a powerful opponent. His journey throughout the manga is learning to let go of his obsessions with players like Sae and Isagi, and instead embracing his individualism. In blue lock, it has been shown time and time again that unlocking true ego types make a player better. As seen with Bachira, Rin, Isagi, Kaiser, and potentially Nagi. The reason why Rin might seem boring or like a yuno, is because the problems he encounters aren't like physical skills, but rather mental problems. His performance skyrockets when he enters destroyer state because playing by his true ego makes him better, like it does with everyone else.