Psyringe: Which team are you playing? Some are better suited to "caging" than others.
JudasIscariot: Tried the Vampires and the Undead, I think. I kind of got a wee bit ticked at the game so I took a break to regain my composure :D.
Vampires are considered one of the weakest teams - the thrall are weak, and while the vampires are strong, they constantly ruin their own turns with bloodlust. Having lots of rerolls is a necessity.
Undead are among the strongest teams (and a personal favorite of mine). With the mummies, you should have good chances to crack an opponent's cage open, or form one on your own if you have the ball. They are very strong, have no disadvantage skills, and are just a little slow, so you need to anticipate where they might be needed. The ghouls are great runners, are quick and agile, have the Dodge skill by default, but are a bit fragile. Skeletons and/or zombies make good linesmen. If you form a cage with the Undead, then it will not be as durable as one formed by e.g. dwarves, but it doesn't need to be - your ghoul just needs to break out at the right moment.
The key to forming or cracking cages is to understand the support rules - i.e., when adjacent players will give bonuses. To form a cage, try to build a web of tackle zones, and also place your players in a way that they support each other.