This is only somewhat true. If you are never an above average skater for your age group then you will never be an above average skater in the NHL. Skating typically never goes from a weakness to a strength between junior and NHL. But it can get up to a level that won't hold a player back in the NHL.
i mean the main reason why Braun went from being an average Dman to what he is now is largely due to the improvements hes made to his skating, and he did it all relatively late in his career.
i dunno who his power skating coach was but hes done wonders for his career .