I really wonder what you think of the term "Improvement".
Is there a steady improvement of quality of tennis in one player's career?
What players are examples of improvement over and over?
Which players had their peaks long ago and will never reach it?
We always say here things like:
"She has to fix her serve and then she will be Top 5."
"If her movement is better, she will improve a lot"
But it is still very hard to improve a single part of the game.
Pattys topspin backhand.
Ivanovics ball toss backhand.
Na Lis mental aspects.
And now: Azarenkas serve.
Can she really improve it?
IMO Azarenka served better in years before than in USO 2012.
She always had brillant 1st serve percentages. Her serve was never really impressive, but she was able to serve with 75% 1st serve.
This summer she was not able to serve with 70+% 1st serve but she did not improve her serve really.
I don't see a steady improvement. Do you?
Best examples for good improvement in the last time:
Serena Williams serve is even better than it was before.
She clearly improved it from a very high to a super high level.
Sara Errani plays better this year. Probably because of the new racquet, her topspin has more pace and her defense is even better than before.
Angelique Kerber did a fantastic job in improving so many parts of her game and her fitness. That was impressive.
Andrea Petkovic did not play natural slice balls, but she tried to mix her game a bit and made improvements in terms of variety.
Agnieszka Radwanskas first serve is better than before. We don't count the tournaments of the last weeks, but before she was serving better since September 2011 than before. She clearly improved her first serve.
Laura Robson did play her best tennis at USO 2012. She fixed her serve and was able to compete on a great level. That was clearly better (in many aspects) than her tournaments before. Probably because of the new coach.
Some parts of the players game remain at the same level for a long time, some parts get better or worse.
But do you think a steady improvement is a logical thing (so, a player gets better and better or is there a peak at some point and afterwards there is a decrease of level of play)?
We always say for young players that they have to improve and than they will be Top xx. It is clear to me that improve the mental aspects with more matches on Tour but to improve a single shot or footwork or variety is very difficult. Especially during the season.
Titel [Suicide T.]: Stuttgart 2017, Doha 2017, Doha 2016, Gstaad 2016, Linz 2015,
Marrakesch 2014, YEC Singapur 2014, Rom 2013, Guangzhou 2013, Peking 2012 & Fes 2012
[TT]: ITF Cagnes-Sur-Mer 2011 & ITF Hechingen 2012
[FITD]: Budapest 2013, s'Hertogenbosch 2016, Peking 2016 & Biel 2017