Players who overcame their weakness?
 

Are there any players who, when they first emerged, were known for a weaker wing, or shot, or movement. Then over time, they developed this weakness into at least a neutral shot, or even better, a strength?

Roddick's backhand apparently improved, but it was always a weakness.

Justine Henin Forehand
Roger Federer Backhand
Mardy Fish movement (lost weight)

Nadal overcame being a one trick clay pony

sharapova's movement and serve -won french
ivanovic's backhand.

I'd say Nadal did a great job improving his serve and the Djoker did much to transform his mental toughness and focus.

Raonic's backhand seems vastly improved from last year. Still iffy once in a while, but I have no doubt it'll be solid eventually.

Murray's forehand used to be terrible. Now it's just as much of a weapon as his backhand if not more. Honestly, its improvement is what transformed him into a grandslam champion.

Roddick's backhand and volleys weren't the greatest at the end of his career, but they were far worse at the beginning.
Also the improvements that Federer made to his mentality and emotion on court.

Nadal, Djokovic, Murray-Everything. It's amazing how much they have upped their game since they first burst onto the scene. I think members of the top four really motivated each other to improve. They're already on a level of their own, but to be able to make a breakthrough even the slightest improvement will make a huge difference. I guess every single member of the big four has been aware of that, and they really worked their asses off to be able to beat each other.

Well, its true that they improved everything about their games, but we are talking about clear weaknesses. Nadal's backhand was horrendous when he first showed up. He improved it a lot. Especially in 2007-2008. Ditto for his serve.

Murray improved his forehand a lot over the past year.

Djokovic has really improved his forehand by a huge margin. If you watch some of his matches from 2005-2006, it used to be a powderpuff shot.

lendl was known as grand slam choker in his early carrier

Also, Djokovic's serve. Incredibly improved. Back in 2010 he was the only one in the top 30 who had a negative aces to double fault ratio. Now his serve is a real weapon.

That's kinda different, isn't it?

Djokovic's serve used to be alright, then Todd Martin made it terrible, now it's alright again.

Milos Raonic has improved his movement and court positioning big time. Training on clay has helped him a lot. still room to grow, but already much improved.

Apparently improved? It became his best shot after his serve from 2006 on-wards.

I think one of the biggest improvements was McEnroe's serve. If you look at early footage, its pretty tame and predictable, but once he perfected that sideways stance and long slow swoop it became a real weapon.

Murray's forehand for sure. His backhand was always his beast shot and imo one of the best backhands in the game currently but he has a brutal forehand now too.

Djokovic's mental focus. The way he turns matches around When he's down is unreal these days. I admit i didnt watch him early on in his career but the way he just switches it on is amazing to watch now.

John overcame his shortcomings by ensuring he has one of the most devastating serves in tennis, this is bad news for the rest of the tour as when his serve is firing John is near impossible to break, this means that his opponent is under the pump in pretty much every single one of their service games knowing that if they get busted once, that is probably the set gone!

Are you Isner's mom ? Seriously, what you are stating has no relation to the question posed by the OP.

The thread is about how players have overcome their weaknesses, the fact of the matter is John has such a brutal serve that he can as he himself said litter up the stat sheet and still win, that is an example of having such a strength that weaknesses are a non issue :)