When it comes to netdecking, I think the most important thing is that you understand the deck you are copying. I find too many people copy a list from top players exactly while not really thinking about it at all. Examine every single card and how it advances your win condition, and potential synergies in the deck. Knowing the purpose of a deck and each card is essential to both understanding how to pilot it and how to refine it. Just because the data looks good doesnt mean the deck is refined either, especially on lower sample sizes.