You're right that the ducking take down is the only way to get a single leg, it's also the most effective way to get a single leg that you don't even need to bother shooting a straight single leg at this moment, there's also the double leg that covers so much range it's stupid. I should be able to sprawl easier if my opponent is shooting a double leg from across the planet.
Ducking doesn't make the single leg semi-viable, with this player it worked every time. If he had ducked under an overhand or a hook, then yeah I'd have no problem with the ducking take down, but the fact of the matter is that you can duck for absolutely no reason and it DRAMATICALLY increases your TD success rate. Maybe the input doesn't work for you, but it most certainly works for this player. In UFC 2 my take down defence was excellent, in this game I am being taken down at will and I can't do anything about it.
You say it comes with a ton of risk. I suppose I could stop it with an uppercut or a knee, but only to get a rock, possibly a flash KO. If you look at this player's record you would see that it's not risky at all for him. He experiences more success doing it over and over again without being penalized enough for it. So much for it being a "risk." It's unstoppable, pretty sure I'm not the only one who agrees about this, watch Martial Mind's videos and he says the same.