The tuba is a very hard instrument to play especially when your using your breath to make a sound. then with all the quavers it makes it even more difficult.

an amazing song that i personally like.

It is my personal opinion that the difficulty of this piece should most likely be switched to Hard. Although the piece is not technically demanding, those tuba players who are looking for medium difficulty pieces are more than likely not going to possess the fluency in the upper register that is required for this piece.