I came across this article on the sports coaching brain site - an great resource for some thought provoking articles. The following quote from the article summed up what coaching is to me, and why the art of coaching is something special:
"evaluate the research, look at the data then use your experience, instinct and intuition to make an intelligent, calculated judgement call."
This article contrasts to the recently increased prominence of sports scientists in the high performance sporting community. Taking a more sophisticated and structured approach to preparing athletes is an important evolution in elite sport, however coaches continue to drive the process of improving sport performance and their experience, instinct and intuition will continue to play the lead role in world leading athlete preparation.
As the article suggests, while sports science can aid athlete preparation and performance, its not as simple as "evidence based" vs "belief based" as some would suggest.
The challenge for coaches is to make sports science work for us, and that the bottom line is that its purpose is to improve performance today.