All sprouts are super high, if not the highest, source of protein, but lentils and other beans act like a starch in your digestive system. The enzyme that breaks down starch in the stomach breaks down beans. Lentils are also one of the rare food groups that have a good amount of carbohydrate as well as high protein content.
The concentrate of protein and enzymes and nutrients in sprouted lentils is more intense than any other food, because it's a seed getting everything ready to grow a plant out of it.
it's hard to find accurate nutritional values of sprouts in their different stages.
Surely, perhaps the longer the sprout the lesser protein it has. That's why I like my sprouts small, where the tail is about the same length as the bean or if a little bigger At least for protein rich sprouts.