Well... after hearing his story... makes me wonder how often the A+ vs A- when both are 5/5, whom has the better potential, or has skills more rounded/workable initially...
Tough spot because it planted a seed of doubt.
Grade ratings say a lot about player's starting skills through provisional salary. So A+ will always be better then A- (assuming they have the same potential) solely because you'll maybe need half of season of training (or more) to get the A- guy to acceptable levels of starting skills - to A+. :) With A+ you get that at the beginning of the season.
From my experience, A+ players have at least mediocre in primary skills for designated position. And beware of 218 cm tall PGs or 185 cm tall Cs :)