I have never been on a hiring committee, so take this post with a pinch of salt. On the other hand, I have some relevant experience so I though it would make a nice comment, but it came out way too long. Best, take it as a "common sense" advice, but shuffle it way down the priority list.
Also, a lot of it feels like obvious things, but I think there is still value in stating them, so that they can be consciously taken into consideration.
1. The hired person must be able to do the work he or she is hired for.
Here I assume the claims below are truthful and well understood (see point 4. for more on the matter).
Claim "can play church organ well", means that you can work hard to obtain your
desired goals, you understand delayed gratification and it is a weak evidence
that you can do the necessary work.
However, "Olympic-level swimmer" suggest there will be some additional obstacles. It means that person will probably want to constantly train to maintain such skill and perhaps go to some competitions which might collide with conferences, workshops, seminars or other scheduled activities. Unless the hiring committee goes for the special perks (like potential publicity gain), it is actually a negative signal.
If you are really serious about leading church choir, it might conflict with your work as well.
2. All else being equal, interesting people make for a better team.
Having an interesting hobby is a weak evidence that you may be an interesting person.
A good team is one that works well together, and having people with good skills is not enough by itself for that. Being a "team-player" is important, but there is another factor that is sometimes overlooked: it is good for the team if its members like each other and like talking to each other. Many of us like working with interesting people. The whole place becomes more enjoyable, and being at work may be a thing to look forward to rather than just a necessary routine. Additional non-work topics provide a social glue that makes team works more smoothly.
3. All else being equal, it is better (in the long run) for the employees to have good work-life balance.
Having hobbies (but not too many) is a weak evidence for having a good work-live balance.
Although be careful, for example it's a feat to sail around the world, but this immense dedication might also mean this person will be gone sailing exactly when its time to write down the thesis (see also point 1. above).
4. Any statement on your resume has also indirect meaning.
You say you can sight-read. So what, so can I (or could). Yet, such a statement does not mean anything. Even if the person reading your resume does know what it means and what it entails, there is no scale to compare yourself against.
One could say in Europe sight-reading is a given if you have any reasonable musical education. But what level of sight-reading?
If you can sight-read like my teacher could or better, then you do have my deepest respect (e.g. Scriabin studies full of accidentals, almost in tempo, and I could spot no mistakes even if I knew the piece recording well; moreover she did not do that by knowing the piece or by ear – she could play my own compositions on the spot too). Yet, how can you convey that information to another person, one that perhaps does not even know what sight-reading is actually about? For example:
- Oh, you can sight-read? Great, I can read notes too!
- That person claims he/she can sight-read?! But Chopin is so hard, nobody can sight-right Chopin. That person must be delusional.
By choosing to put some information on your resume you make a decision. These decisions may indirectly reveal something you won't like. Even tiniest details, like punctuation (see Lessons from a year’s worth of hiring data), might matter. If you choose to claim that you "can sight-read", then the hiring committee might misunderstand it as (I am exaggerating on purpose) "puts value in unknown, obscure skills", "has problems communicating clearly" or "does not understand what skills are relevant to the position".
While I would encourage you to include information on your other skills, do so only if you can communicate them clearly without putting too much emphasis. Furthermore, remember the hiring committee will be looking at this from their perspective, in particular "leading a musical ensemble in years 2014-2017" might be more relevant that "can sight-read".
I hope this helps ;-)