Jordan Horston is not the best example of talented Tennessee players who failed to develop. She played four solid years as a Lady Vol, and played very effectively against UConn in each year's game. She was drafted in the first round by the Seattle Storm and has played well for them.
There are players from the mid-2010's (the late Holly Warlick years, e.g. Mercedes Russell and Cierra Burdick) to whom your comment is more applicable.
I believe that although Jordan Horston was recruited by Holly, she played all four years under Kelly, which may account for the different result.