To me the main storyline of the series is that the Hawks had a lot of options (and used them all) to stop the Knicks best player) while the Knicks had nobody to stop the Hawks best player. Atlanta was able to throw a whole lot of long bodies at Randle to prevent him from taking over the game, and the Knicks didn't have enough offensive firepower elsewhere on the roster to make up for that. Barrett is not an A-list player. Rose is a total pro, but he can't be your bellcow. Quickley isn't ready. And Randle is good, but he isn't LeBron.
Meanwhile, Atlanta has a whole bunch of good pieces around Trae Young, and the Knicks just didn't have a guard who was capable of playing with him. Personally I would have tried to attack him at the other end of the floor either by playing Quickley more or trying to iso him, but I"m not going to second-guess Thibs, he's an excellent coach.
Knicks need to add a top-flight point guard and upgrade some of the other pieces, plus get development from Barrett, Quickley, Toppin. Lonzo Ball might be a good option for them.