This is an oversimplification. It's not the slice that bothers Serena. It's the lack of rhythm. So a heavy topspin shot, followed by a slice and another slice then a hard flat shot etc. It's this combo (amongst other things) that kept Serena on her toes against Henin and to a lesser extent Mauresmo.
Well yes, I didn't mean to say that the slice on it's own would beat Serena lol a player who does that on it's own has very little chances --
As you stated, a slice combined with any other shot or group of shots, could be a hard ball, a top spin shot with a wider of shorter angle etc... would be disrupting to her rhythm...
Actually I believe a player like Bernard Tomic's talent would something I would like to see in the WTA one day, he doesn't over-loop or spin his shots like Murray, he has these sort of relatively flat shots that he varies in pace, angles etc... combined with his good 1H slice + variety... and suddenly he can just change rhythm from almost anywhere on the court for a winner...
You make it sound like it's the easiest thing in the world to do, and if done will guarantee success. Mauresmo does this well, blocking the serve back. In fact, she used it to great effect in Wimbledon 06 SF against Maria to get her off her game. However, it didn't work on Serena (and Serena wasn't serving as well back then). Serena moves too well and will make you pay for a blocked service return, especially if it lands short.
I think Mauresmo didn't have a big enough game for Serena which for comparison Justine had... Mauresmo was some kind of artist IMO and it's complicated to always overtake big babes with so much variances -- Justine she with the exceptional variety she had was also able to go toe to toe with Serena and completely blow her off the court at times and there's nothing Serena could do than just admire what talent really looked like... Mauresmo was never really able to show this kind of big babe tennis but her manner of being aggressive was still as beautiful, transitioning forward, S&V, R&V etc...
When Justine came back she decided to go all out and she lost that balance she had from her glory days... but Justine's offense at her peak was just beautiful, she could take so much time away from Serena - half-volleying shots, taking the ball early, stepping into each and every ball, transitioning forward etc...
I make it sound like it's easy but that's the most effective strategy when playing Serena's serve... I'm not saying that it you will win 100% of points doing so but you will win 30 or 40% of points on her service games as opposed to 3 or 4% when you're trying to play a full swing... and that's all the problems with the girls, they prefer win no points with UEs since the return of serves than at least 2 out of 4 in exchanges which is already a good start.
Serena is very sensitive in exchanges, people try to make her footwork look some kind of Genius in action but she's just explosive that's all, she's easy to put on stretch if you have some kind of correct strategy and if you have no problems with power... the power that she generates in her shots persistently is a barrier which makes it difficult to take over her overall weak movement...
Bojana often was attempting in all struggles at times in the start of match to fixate Serena in the diagonals with some short angles or lift balls in the long diagonal and get the shot to redirect DTL and put Serena in difficulty - I found the idea correct at first but problem her footwork sucked and the slightest acceleration of the american was destabilizing to her so she could barely stay toe to toe in genuine rallies more than 3 or 4 shots without being rocked to get that DTL BH or FH... and her attempts of taking the DTL often resulted in huge mishits, UEs etc... another thing her rally balls are meh, no weight into them, no intent...
I personally saw nothing that impressive about Serena so much her opponent was quality-less last night !
Whose serve is better and more effective?
Serena's serve is good I'm not saying differently but you must admit thought that the lack of technique on the WTA tour participates a lot in it's so said greatness...
IK this is virtually impossible but I would just like to see Serena's unique serve against the return of serves of Federer, Murray, Djokovic or even Nadal to see how many shots more would they bring into play with their technique which is much much much more varied than on the WTA tour... I think it's not even close.
Very few girls can return a 123 mph serve with there go to grip, you have Kvitova, Azarenka from the top of my head - when you do not have these natural returning skills it makes no sense trying to return like these girls, try something else anyways practice something else, you're losing 70-80% of points anyways what would it change for you to just simply put a quality ball back into play ? You're already losing more than half the points any ways. I'm not saying you have to do that on every every serve.