wrist strength for serving

Hi,

I have played a couple of difficult players who have spinny serves, say player A and player B.  Both players are heavy-set, with what I imagine must be thick, strong wrists. Player A doesn't serve with a violent brush (US player and writer Danny Seemiller says serves should have such a brush), but his serves have incredible spin. He puts most of them deep into my backhand corner, with heavy back/side spin. They all want to go into the bottom of the net. Worse, he can switch to top/side and I can't tell the difference. Either way he gets a lot of spin. And his serving action is so casual, with a gentle roll of the wrist. Unfortunately, I can't tell which serve is which even when watching from out of the court. He can easily beat many people who have a technically stronger game. And he admits that he doesn't have a clue about the mechanics of his miracle serve.

Player B's serves are totally different. For some reason, the ball seems to hop or jump suddenly after bouncing on my side. I don't know how he does it. Both players have effective serves, and can serve me off. I think the only way to deal with them is to have a big loop, which I haven't.

I can get some spin on my serves, but they don't give me a big advantage. Apart from brushing speed and wrist snap, is wrist strength itself a factor (which it seems to be for players A and B)? and if so, how would I improve it? (My wrists might be too thin)

BTW: I've heard Paul Pinkewich comment on Werner Schlager's serves at one Australian Open and Paul said that Werner does a lot of weight training in order to be able to snap his wrist. He pointed out that Werner has an odd-looking muscle in his arm (?) resulting from his training. Sounds odd. I didn't spot the defect.

Cheers,

Andrew.