Why? Mainly because the series now rely on recycled jokes from past episodes and pop culture references.
What used to be a fantastically funny series with jokes worthy of Monty Python has now become merely another comedy show. I hate to say this, but I honestly do think Yu-Gi-Oh: The Abridged Series is finally starting to lose its edge. This series hasn't really began to take off yet, but I must say the first episode very much impressed me.
