I think all three are important..
Skill, the art of knowing what to do, how to do it, and under any circumstances. Experience, the more years you have the more good, bad or indifferent experiences you have to learn from. No matter how much someone applies them selves or reads the books you will not encounter every situation, to possibly learn from, in two or three years on the water, sailing only bays or lakes. Sailing is a life long learning event that I don't believe is ever truly mastered. You are a lifelong student of the sea and no one can "own" it 100%. I learn something new every time I go out and if I don't it means I was not applying my self or paying attention. Knowledge, is the all powerful tool but if one has no clue how to get it from the brain to the fingers or translate that knowledge into an actual repair at sea, a make shift rudder, or a sail change in 35 knots and 6 foot seas then the knowledge is useless. A case in point, I've been on the water a long time and have had to untangle lobster pots from rudders, props & keels more times than I'd like to admit. I have made dives, at sea, and in bays, literally 50+ times to untangle lines fouled. In Maine it's almost unavoidable like finding the bottom in the Chess. Two summers ago at the mouth of a very large, powerful river in Maine we snagged a pot that had been taken just under the surface by the strong current. I did everything I had learned in the past, from multiple events/experiences, like attaching my dive knife to my wrist lanyard using a better method, putting on my gloves so I don't cut myself on the prop or the "so called" line cutter, attaching my safety line so I don't get separated from the boat, putting on my wet suit & keeping all these items in a quickly accessible bag so I can be in the water in under 2 minutes if I have to. Well I had done this numerous times in my life but learned something NEW that day too as one should. It was very rough and the boat was being tossed around fairly abruptly. On my second dive under as I came up to grab for the prop shaft the hull came down on my head hard! Now this had never happened before, I never read about it in any of my books, and I was always careful and confident that I could hold myself off of the hull with my hand on the prop shaft but I was wrong! I learned something that day, like many others, and now have an 8mm wet suit hat, with extra foam padding, for cold water divers to prevent me from getting knocked out or severely cutting my head. Mellon padding is good as I learned that day! Every dive, like every sail, I learned something. Once it was dropping my knife due to a poorly executed lanyard, once was holding on to the prop shaft with one hand while working with the other, once was wear fins etc. etc.. These particular things I learned are not in your average sailing books and have to be learned from experience, however you care to define experience, or reading ones account of it on here. I will never go under my boat again without my "padded hat".Experience is a broad term, meaning one thing to one person and another to someone else, and on here has become synonymous with the famous Bill Clinton-ism "well it depends on what the definition of the word "is" is". To me experience means you have experienced a lot, learned form it and grown from your experiences. I include skill, knowledge, individual learning experiences and mechanical aptitudes within my own personal definition.My wife is in the medical field and they refer to it as clinical experience. Experience being the all encompassing term including knowledge and skill.My opinion is that the cumulative years will eventually lead to experience regardless of how well you apply your self. Yet if you truly apply your self you can accelerate the experience learning curve but never totally replace time and the thousands of experiences gained over a longer period of years spent doing. Sit down and talk with some local sailing legends and see just how much they know and I think you'll be amazed. Dodge Morgan and Merle Hallett are a couple that come to for me & I doubt with their combined 120+ years of experience there isn't much those two have not encountered or experienced regardless of how well Merle applies himself at 80+ years of age. I bet both of them will be the first to admit they still learn too..