ALL INITIAL GAINS ARE NEURAL. You, and all lifters need to understand that. People add 25 lbs to their bench, look at their pecs and say, but how come they aren’t any bigger? The answer is why would they be when all that happened was the brain/neural pathway/motor units improved their ability to send a strong signal to fire. Recruitment pattern gains first, then only after a certain amount of threshold weight has been achieved does the body adapt with new muscle mass. Strength vs size gains are rarely linear.