One thing that has always baffled me about Venus is her lack of a true kick serve. At her height, and her racket acceleration, her kick serve should be nasty. In my honest opinion, if she had a real (not one of her fantasy land "my kick serves were bouncing pretty high") kick serve, she wouldn't have lost at least 20 matches over the years.
Now the question is, why? Kick serves are fairly easy to hit. Women have some problems with it, but women also have problems hitting 120 MPH serves. So that excuse doesn't work. People could say well its her coach, but Serena has about a good of a kick serve as you can expect from a female, and last time I check they have the same coach.
Venus has had this problem from day 1. Her second serve has gotten marginally better, but it still always goes to the forehand side or in the middle of the box more time than not. And she obviously reduces her racket head speed (which you are NOT supposed to do. Good players actually increase it) and bobs her head down. I remember reading an interview when Venus was 10 saying how she needed work on her second serve.
Personally, I think its a combination of things. First of all I think Venus is in denial that her second serve is relatively poor, and secondly I think its her service motion. It has so many flaws, but her racket head acceleration on the first serve smooths them out as her body can balance itself out, when its slower, not so much.
I also think it shows that Serena got substantial outside instruction. It has always seemed to me that Serena would go elsewhere if she wasn't satisfied with her parents. She is a far more complete player than her sister, not because of more talent per se, but because shes gone to others to learn how to hit shots. For example, many posters on this board could probably lob or hit a kick serve better than Venus can. Serena went and learned those shots to perfection - I really don't think it came from Richard or Oracene.
Obviously, she is a great player and I'm a huge (huge) fan, but I'm one of the realistic ones, and I'm not too confident of her consistently beating Henin without a kicker, and I dont' see her getting one at this point.
So the questions is....why!?
That's an interesting question. Can a player hit a convincing kick serve when they consistently toss the ball to the right?
The players who have technically poor second serves all have a common trait, they toss the ball quite far to the right, hoping to come over it with slice hence the reason their serves going to the opponents forehand more often than not, these players include Dementieva (of course), Venus, Jennifer Capriati, Jankovic.
The players who technically have the best second serves all toss the ball above their head or slightly to the left so they can keep their form and get the racquet acceleration required. I think of Svetlana, Serena, Lindsay Davenport, these girls never suffer a crisis of confidence on the serve because of rock solid technique.
I find Henin, Sharapova and Mauresmo are in between. Sharapova initially had very good form but has still managed to lose confidence but that could be due to shoulder problems. Henin and Mauresmo are prone to double faults. Henin doesn't have a kicker as such but she uses a lot of spin so the ball bites off the court and shoots so it can still be very effective.
It will be quite difficult for Venus to improve her second serve at this stage of her career unless she is prepared to put a lot of work in during the off season.