Well I guess I may have a little different take on things. Sportsmanship ( to me) typically has to do with the attitude an athlete has towards others that play the game. It has very little to do with the skill an athlete has in his/her respective sport.
For example, you can be a great baseball player ( Barry Bonds) but his sportsmanship towards the game and other players ( and fans) was horrible. We won't even deal with ethics in this paticular discussion.
You can be a very mediocore athelete, but still have great sportsmanship. Its all about attitude.
Musicianship ( to me) has to do with techinical ability and the amount of time you put towards developing your craft.
I don't believe that you can be a mediocore musician and have great musicianship.
But you have to get past perceptions to be able to really tell. You might hae a musician who can kill the piano ( but can only do it in one key). Well, that is a mediocore musician and he has poor musicianship.
You might not be able to play every style expertly, but you can play in any key, play solo or in a band, can explain what you are playing, can read music ( maybe not expertly) as well as pick up a song on the fly. Then that person, while they may not be considered professional, has very good musicianship. I would venture to say that a person like that would also be considered "expierenced" on whatever they consider to be their instrument of choice. They are definitely not beginner or mediocore.
Additionally, that person can have great musicianship, and still be a nasty/conceited musician.
Thats just my take on it.
Jlewis