Han Xin's story sits behind this stick like a quiet rebuke to anyone judging themselves by the wrong yardstick. He was the same person before and after Liu Bang noticed him; what changed was the room he stood in, the questions he was asked, the work he was given. The verse holds that figure up to you and asks what you see. If you came to the cylinder asking whether you are clever enough, whether you will pass, whether you have what it takes, the stick is gently sidestepping the question. It points instead at the setting you have placed yourself in, and whether that setting actually lets your kind of thinking show.
Most likely you already sense this. The subject that drains you, the study group where you go quiet, the format of exam that flatters memory over reasoning, the teacher whose feedback you have stopped reading carefully — these are the village street where Han Xin was mocked, not proof of your ceiling. Moderately good means the talent is real and the door exists, but the door is not the one directly in front of you. Some honest reshuffling of where and how you study is the work the verse is reflecting back.