A different type of thread, interesting thread Fantasy Hero. As others have said, there are some very knowledgable posters on this forum, and sure you don't have to be a top player to be a good coach, in fact in most sports including football, some of the best coaches never played to any premium level at all, like Arrigo Sacchi and Jose Mourinho to name two. Gerrard Houllier was a schoolteacher before becomming a football coach and manager. I actually did a couple of coaching courses (tennis that is) exactly 10 years ago in 2002.
How about Victoria Azarenka? Probably the ultimate modern player in this era of slower surfaces. Very similar to a Novak Djokovic and Rafael Nadal as she is prepared to grind for a long time to win a tennis match and has developed a good temperment, like Djokovic something she has had to work on. Very solid technique indeed.
How to beat her? That's very difficult because of her consistent level, it never really drops so you have to raise your level and try to get her on the move. Despite the fact she has worked hard on her movement, she is not the most natural mover around the court so she can be taken out of her comfort zone by getting her pulled out wide and then with drop shots.
Azarenka, like Djokovic, plus players like Courier and Lendl in the past, they are vulnerable to talented shotmakers. So Azarenka is vulnerable to Petra Kvitova because Kvitova goes for her shots and raises her game which Azarenka finds unsettling as a player who wants a rthythm. Djokovic has this problem with Federer, Courier and Agassi had that problem with Sampras and Lendl had that problem with Becker. Azarenka also has a problem with Serena's serve and athleticism (but everyone has a problem with Serena these days).
How to get Azarenka to win? Quite simple I think, her technique and temperment is so good that her consistency will beat almost everyone all of the time. Plus like Lendl, her philosophy is to do it to you before you do it to her "crush or be crushed" is the phrase that was coined. She wants to jerk you around side to side like Agassi used to do, dictating the middle of the court. However, that's why players like that don't like shotmakers, because shotmakers take you out of that comfort zone of the middle of the court.
Azarenka is also vulnerable to players with good serves, since she doesn't have one herself.
Another reason why Petra gives her trouble, is because Petra has good enough hands to play the fast baseline game Azarenka likes, and can redirect Azarenka's shots for those winners you mentioned. Petra also has the power, hands (from the baseline) and the touch/off speed shots to make Azarenka uncomfortable. This is cause Kvitova doesn't respect Azarenka's power or serve, and has good enough hands to play her type of game.
Azarenka did well against Sharapova on hardcourts earlier this year, cause Sharapova doesn't have good enough hands to play as close and fast to the baseline that Azarenka likes, and can't redirect as well, so she make errors or gets pulled out of court for Azarenka winners.
Sharapova's serve doesn't seem to bother Aza as much on hardcourts as well.
And of course Serena has a great serve, power (she may not have the best hands anymore), but she can run down balls when she wants or is in good shape. So of course she gives Azarenka trouble because of this (as well as Serena revenge and intimidation from Miami years ago, that Aza hasn't seemed to shake).