Every technique done incorrectly is dangerous. That’s why it’s incorrect. The issue is, of course, how we define it. In jujutsu, for example, where one considers falling on a hard surface, bad sasae is as harmful as any other throw because chances are you won’t be able to fight after it and eventually save your life. The fact that the mat in dojo makes a bad performance less painful is in that regard irrelevant. In judo, however, the situation is somewhat different which in return tends to stretch out the definition of a correct throw.
In the presented paper, researchers calculated the impact of drop on knees in seoi otoshi among various judokas. Presumably, less impact would mean a more “correct” performance. The problem is that the actual object of their research wasn’t seoi otoshi but rather “a man dropping on his knees”. The two are not the same.
A throw, the way it appears, is a product of interaction between desired effects, perceived opponent’s vulnerabilities and potential risks. In other words, it exists as such because of the circumstances not in spite of them. Goyko throws are ways of adjusting to the situation (according to the defined principles) not a collection of one-size-fits-all tricks.
However, as it can be concluded from the pictures, the researchers obviously disregarded elements integral to seoi otoshi and reduced the whole idea to the knee drop. Anyone with little common sense knows that dropping to one’s knees hurts. The only way you want to go for it is if, of course, there is some way to reduce the impact. Yet, by having uke take a tall and unstable posture researchers created a setup that does exactly the opposite. The conclusion: precise measuring confirms that incorrect technique is bad kung fu?!
The research measurements actually have no relation to judo technique called seoi otoshi considering that an incorrect technique is actually not a technique at all but a failure.