#4 Stabilising the defense and coping with Umtiti's absence
FC Barcelona in their final season under Luis Enrique were near-horrific in defense. Everyone would foresee them conceding two or three goals against good oppositions. People thought PSG would not be the one who could take advantage of the poor defense, but 4-0 happened. People thought Higuain and Dybala would destroy Barcelona's defense at Turin, it happened. People thought Madrid would win 3-1 in the Clasico, thanks to Messi they lost in the 92nd minute but still scored two goals. The defense was never Barcelona's strength under Enrique.
Ernesto Valverde moved a bit to 4-4-2 and added the much-needed stability in the defense. There were not many instances when Barcelona conceded much last season. They conceded 29 goals in 2017/18 compared to 37 in 2016/17. Also, 5 goals came in Matchday 37 which tells us how solid they were in the back.
Another important thing that Valverde did well and is still doing well is coping with Umtiti's absence. The Frenchman has been out for a combined 177 days in Valverde's tenure including 2018/19 season. Last season he had muscle problems and missed 9 games between December 2017 and January 2018, one of which was the Clasico. However, Valverde dealt with the situation, trusting Vermaelen in the center-back spot, with no backup signing in the winter transfer window.
This season also, Umtiti has been out for almost 17 games now. Do Barcelona really seem to be missing him? Valverde has done really well in instilling Lenglet into the team. He has slowly integrated Lenglet that Barcelona haven't felt Umtiti's absence, despite him being the best defender in the team. He has used Chumi when required as well.
This is one of the major aspects of Valverde's management.