The issue when playing cav is if you have large numbers and you fight against equal amounts of infantry / archers, any decent archer / xbow can kill an arabian horse (maybe the most used horse [considered the most op]) from a very safe distance in 2 good shots, the single factor being the rangers accuracy.
Say we take maybe 15 footmen of our 50 to be archers, by the time the cav even reaches the infantry to do all this fancy circling they've lost 10 horses (providing 1/3 shots miss and all the archers know to shoot the horses [they should as they are in an organised group afterall]). These cav can't really play any immediate part on their own so are for arguments sake neutralised.
Now for cav to take on this group they are going to need to do more than just charge straight into the footmen at once, so they are going to circle once again at as safe a distance as they can, maybe limiting the archers to an accuracy of 1/3 shots hitting. We can expect a further 5 horses to drop providing they all stay close enough to be an immediate concern while remaining a relatively safe distance from the bows. There is now 35 full health - wounded horsemen left to take on a group of 50 footmen.
The cav are now going to engage possibly with the aid of any dehorsed allies (these will be mopped up pretty fast as they will be too few to fix an entire group, will merely get swarmed and killed) . Providing you even have as few as 10 pikes, each one of those pikes should be able to catch at least one horsemen who will die on stopping due to being mobbed, however the horses will a few kills themselves, if they are lucky they can pick off 10 stragglers including if they have a banner of lucky clovers a pikeman.
We're now down to the remainder of horsemen circling / retreating / suiciding into pikes, they cant just keep attacking as a single charge will remove all the momentum and the cav will need to regroup. We now have 25 horsemen vs 40 infantry, some with bows, many with pikes. They can circle and charge all they like but the odds are not with them, they are relying on one thing to win and this is key. The infantry group with their new found success will split and break out of organisation to chase cav, and this is what causes infantry to die everytime... I have seen a group of footmen demolish a huge amount of cav, only for the few skilled cav to pick them off as they cockily split up, then people whine that cav are op