The main point in Ericsson et. Al.(1993) is that in order to achieve expert performance, one must engage in deliberate practice with the explicit goal of constant improvement.
This theory further dismisses to a large extent the role of genetics, in which Ericsson reasons that there has been no great correlations between the attainment of superior performance and inherited traits. The purpose of this paper is to show agreement with Ericsson's theory, but only to the extent that deliberate practice is just one of many factors which must be included in order to gain expert status. …