Chaos can be a good team once it has developed, but to start off with no players with block is a nightmare. You can develop each player into specialists fairly easyand can also have mutations on advance rolls, which can help develop players further.
The chaos warriors start at ST 4 and the beastmen are ST 3 (4 if they blitz with horns), making it a nice bashy team (once you get block for everyone).
Tactics are usually cage and fight until no one can fight back
Though with faster dodgy teams, you may have trouble trying to keep up.