Well, wood elf defense can be a hard thing but also a very effective one, if done correctly. You need to take care of several things.
a) You will never stand up against anyone in a straight fight. So be sure to offer your opponent as few blocks as possible. As mentioned, when he moves towards you, alwys try and dodge away one square or two, offering as little advancement space for your oppo. Your goal is to delay his advance as much as possible, so he is getting nervous and eventually makes a mistake for you to exploit.
b) Be sure to always have someone available for those aforementioned mistakes. Have your wardancers or maybe a thrower nearby, in case he is losing the ball, so you have someone to dash in and grab it from right under their nose. After that get the ball to safety, handover/quick-pass it to someone else, who tzhen makes a run for it.
c) Always have someone in scoring range. Even your linemen have a very good speed, place one in your oppos back field, so if the opportunity arises, pop the ball loose (see b)) and then get it to your scorer (have thrower handy). There is nothing like a touchdown in the same turn, when your oppo loses the ball!
d) Play an aggressive defense. When your opponent cages up (i.e. surrounds his ball carrier with lots of team mates), put a few guys in tacklezones on the rear of his cage. That forces him to open up the cage and may give your wardancers the opportunity for a shot at the ball carrier. Make sure, your WDs have tackle or strip ball, proves to be invaluable.
e) Don't let them cage up. Put pressure on them from the moment you kick. Have someone with the kick skill and place the ball far in their half. Due to thier slow speed, orcs usually can't get to the ball then, or at least not get it into a safe cage. That's, when you need to strike. Your fast movers (Wardancers, perhaps catchers) can then try to dash in and rid them of the ball, before they can get a tight grip on it.
This is all the advice I can give you without reaching a word count of over 1000.

Try to integrate this into your play and you'll be giving them a hard time. If you need more advice, you can always come back.
