A good example is the game of golf I recently took up (because I don't have enough frustrations in my life). I have had instructions from a golf pro to show me how to swing and how to address the ball. So I spent some time practicing but I knew there had to be something to help me hit the ball better. People kept using terms like "open face" and "close face" the club when hitting the ball. I didn't know what they meant until my next lesson - what a difference that made in the way I hit the ball.
Selling and the skills needed to be a good salesperson are very much like learning the game of golf. Until you fully understand all the skills and how they are used, how can you expect to be a better salesperson? It is amazing how many people in my selling workshops have been "out selling" for many years, but they've never been formally trained to sell. Selling is a learned ability like math or reading; you don't just start out and know how to sell. You may have some of the traits needed to be a super salesperson, but you'll never learn the skills until you attend a sales seminar.