1. Always had the feeling that even pre BXJF, he wasn't that much weaker than ZLC. Given his sneaky nature, it was very likely he was hiding his true abilities.
2. He used needles. There's only one other person who used needles....DFBB. Could it be that YBQ could actually had figured out that the greatness of KHBD/BXJF lies in the essence of speed? And needles are actually more useful than swords in this scenario? Yes, he did repeat those stances, but perhaps he thought the essence of BXJF lies in speed and stances? Given a little bit more time, YBQ might be able to figure out. YBQ was after all, from the Qi faction, and thus, not as talented when it came to swordplay?
3. We often cite that his internal is lower than Bujie Monk, since the monk could suppress the 6 Fairies' streams. However, the monk suppressed. If I recall right, YBQ could dissipate (much harder imo) the streams with his Zixia Shengong, but that would leave him exhausted and vulnerable. He could heal LHC, he chose not to.
4. Somehow, JY likes to rate inner energy cultivation skills that has healing properties highly. For instance, 9yin, 9yang and YJJ all turned ordinary fighters into top notch fighters. I'm not saying ZXSG is at that level, but it is interesting to note that ZXSG seem to have healing properties as well (which was why LHC was given ZXSG to learn when he first got injured).