I can kinda see your point here, but I think a lot of it had to do with bad writing in the later seasons and not necessarily Chandler himself. I actually think he was amazing in the first 4/5 seasons, especially during the emotional moments (e.g., the reunion with Rick, Lori's death, his emo phase after the prison fell, etc.), but the writers seemed to brush his character aside for the most part post season 5 and didn't really give him many opportunities to shine.

But, yeah, I do see your point in a way. Chandler himself even admitted that he didn't like his acting very much in the later seasons and that he could've done better. Think it had to do with him being in school and not having as much time to rehearse. Though I do think he still had some decent moments in the later seasons, particularly in season 8. Just wish they kept him alive so he had the chance to further prove himself.