Focus on Your Weaknesses?

Here's a question.
If your child came home with a report card with the following grades ...
Math = A
Computer Science = B
Social Studies = B
English = C
Physics = F
Which grade would you focus the most attention on?  The F is usually the popular answer.
The same thing goes in baseball.  A player asks the coach what areas they are weakest in so that the player can focus most of his attention in that area of the game.
But why?  The student above probably hates physics so saying something like "the next two weeks you are going to spend all your evenings and weekends studying physics!" is the kid's worst nightmare.  Pick something you hate doing and imagine having to focus all your attention on that thing for a month.  How are you going to like the next month of your life?
If a player has an "A" in running speed and an "F" in hitting for power, do you want him to focus more attention on hitting for power?  I wouldn't.  I'd want the player to maximize his strength and minimize his weakness.  He should become an expert at base running, reading pitchers' moves, and stealing.  His hitting work should focus on line drives and ground balls, using the entire field, working the count, and bunting.
In life and in baseball, you need to find something you are good at and run with it.  That's what makes you unique.  That's your angle at success.  Value comes with scarcity.  If you are unique, your talent is scarce and therefore worth something.  It makes no sense to focus too much on a weakness.  Someone out there is strong in your area of weakness and loves doing it.  Let them have it.

Jamie Moyer didn't become a MLB
pitcher by focussing on his weakness.

Imagine if Jamie Moyer woke up one day early in his career and said "I'm weak in the area of velocity so I think I'll focus most of my attention on building arm strength so I can throw 94mph."  The result surely would have been a quick end to his career.  He instead chose to identify his strength and focus on maximizing that strength.  He became unique and continued to have value.
Don't get me wrong, I'm not saying to ignore your weaknesses and just accept the "F".  Putting more attention on that area or making an adjustment in how you approach it, is necessary for overall improvement.  However,  use your time more wisely and focus on the more valuable area(s) of your game/life.  Focus on the A's.