After over 100 games in skirmish, cav is by far the class that needs looking at first imo. Firstly I believe that the horses are way to tanky unless you get a clean hit on the rider as they are running at you, which is too much of a risk to open yourself up like that as most times you will loose the trade. I think they should just limit cav to 2 players in skirmish, too many games with 6 cav players in pubs. Also maybe look at making spears more effective against them I feel that if you have archers just let them kill the horses so you can finish them off when they fall of their horse.
TLDR: Horse too tank, spear too weak