Butler had a fantastic series, but let's not act like he does that night in and night out. He doesn't. In the 17 playoff games he played last year, he had as many or more FGA's than points in 5 of those games. That is 5 games of awful shooting. After going up 2-1, in a game Butler barely played, the C's took a 3-2 lead in a very large part because Butler was 3 of 14 and then 4 of 18 in those 2 games. He played very well in games 6 and 7, but even in game 7, Tatum was the best player on the floor in the 4th quarter of that double elimination game (Tatum outplayed Butler in the 2nd half overall as well in game 7). Butler had an excellent 1st half in game 7, but he was -6, and he just faded as the game went on, while Tatum just got better and better.
The simple reality is, there are very few players like Lebron James and Kevin Durant. That night in and night out you can pencil in for a good to great game when they are in the their prime (and even they both have had a stinker every once in awhile). Most players are more Jimmy Butler esque i.e. they can look like the best player in the world at times, but other times, they just blow. I do think Tatum can grow more and be more like Lebron or KD, but right now he is more like Jimmy and that is fine.