I explain things to students all the time, but they must first have developed the basic skill to understand the criticism or instruction. I've told some students repeatedly, the same information over and over again... and it doesn't "stick"... others, I teach one time, and they "do it".
There has to be understanding "between" teachers and students... and the proof of it is on the floor. Many instructional methods involve thousands of repetetive actions to build "muscle memory"... some involve hesitations or redirection... not all instructions are the same or with the same intent. How well the instructional process is going is shown "on the floor" during randori and free practice.
Sometimes, but not often, you simply have a student that "doesn't get it"... no matter how much instruction you give them, or how you craft the information. Martial arts are physical skills learned through a combination of mental exercise and physical exercise... teachers are "information in motion".
My back limits me from teaching skills I once taught, but I have students that can teach them, as they were taught. When I first started training, I tried to pay my sensei for lessons... his answer was simply to "pass it on" to others... which I have done, and have been doing for 45 years. How well it's worked out is "on the floor" with anybody I've trained... not confrontation, but "before you" in either randori, free practice, or instructing.