Honestly I'm really not a diet guy. I do not consider myself a nutritional expert and except for some rare cases I'm not the one handling the diet portion of my client. I refer them to someone I work with and they get their own nutritionist.
I'm not one of those coaches who claim to be the best at everything. I consider myself a master of training but not about nutrition... not to mention that it's not a subject that really interest me. So I can't say that I studied diet for Easy Hardgainers in depth. The only thing I noticed is that the easy hardgainers I worked with who progressed the most where eating a lot of carbs.