The kicker is that 10 ride character doesn't need PS, as long as he can build up speed for the speed bonus. This is basically the build that goes 10 ride, convert for enough strength to wield heavy lance, any points left goes to WM for polearms. No athletics, nothing. Athletics on cav just shows you have not made up your mind about being cav anyways.
These guys are what I fear as a HA, since 10 ride can out ride most horse archers, leaving little room for mistakes, especially if 2 are working together as a team to pincer you. You either shoot him down in those few seconds, or very likey get dehorsed to die. When HA screen is down they then go own infantry support cav. After letting their team get complete cavalry superiority, they can just hang back giving enemy pedestrian duelers another thing to worry about, and back stab any that are not paying attention.
Obviously the map has to be one of the semi plausible ones that allow cav jousts and duels to be a factor, otherwise infantry support cav rules.
The build is not very good at killing crunchies, but is very good in cav fights, since speed and turning is everything. Low PS is not really a problem, especially with speed bonus since everyone rides a light horse, and most hits land on the unarmoured horse. There are a few Euro/ Russian clanners who have this build, but I am not sure whether the famous solo hotshots like oberyn uses it.
This build was not so hot pre big patch, since the infantry support cav on armoured horses (but most likely wearing lighter armour due to low strength) could exchange lance hits with light horses and still come out on top. Plus heavy (as in heavy horse) cav often had way more ride too, negating most of the speed advantage. Post patch it seems to have a surge in popularity.