Be sure to make a distinction between the mental tools of knowledge and those of analysis. Most people focus on the former, but it's the latter that make you expert, if for no other reason than the fact that the results of analysis themselves become knowledge, usually of a more useful nature (abstractions, relationships, etc.)
The article asserts that "success builds on success, because each accomplishment can strengthen a child's motivation." The phrasing of this statement makes it sound like speculation based on observation, not science. In my experience, it is more likely that the mental and physical tools that have been so well trained to accomplish one task find other tasks requiring similar techniques to be less difficult. If the difficulty reduces while the reward increases, you have motivation. Risk/effort -> reward analysis.
The case of D.H, who improved his chess skill by acquiring the knowledge of chess positions and associated strategies, but who did not exhibit additional analytical skills, is worth noting. This is a useful technique, and can be advantageous to a degree. An analogous situation in the IT world would be the definition of programming patterns ... defined techniques used to solve a particular large-scale problem. It's useful to have programmers on staff who know their patterns. However, don't ever mistake them for analysts. When the problems get particularly difficult, you want someone around who can define new patterns or not be limited in their creativity to what fits into a particular structure.
With regard to the chunking theory, please keep in mind your math theory lessons. A symbol can be viewed as equivalent to a function. Also, a symbol for a function can look exactly like the function. A collection of chess pieces in a particular pattern is not merely the data being stored in your head, but is also the visual, spacial, sequential, whatever pattern being used as the referent. Nifty thing ... a manipulated pattern of the knowledge resulting in a new pattern can then be used as a referent for another pattern.