1. He's an excellent defensive coach
One of the main selling points of going and getting Vogel to replace Monty Williams last summer was the eye he had to build an elite defensive scheme. The offensive side of things was meant to be overlooked by Young, while any team with the aforementioned three stars should be above average in that area, no questions asked.
The Suns did finish 10th in offensive rating, yet the 12th they managed defensively (113.7) was somehow overlooked. This despite Vogel managing to put together an above average defensive group with his three best backcourt players being Booker, Beal and Grayson Allen, while Durant spent some time playing the five.
Indeed Durant had an All-Defense case that we tried to make when he didn't receive a single vote for Defensive Player of the Year, while Nurkic and Eubanks as the center rotation isn't going to strike fear into many legitimate contenders. Yet despite all of this - and players like Keita Bates-Diop being sent packing at the trade deadline - Vogel had them playing reasonably well on that end.
Coach Budenholzer is going to come in with a more free-flowing offensive scheme, and the Suns will likely benefit from that. Then again, scoring never really seemed to be the problem. To finish 10th in a poor season for them proves that. On the other side of the court however, Vogel is going to be missed immediately, and only then will we truly see what miracles he was working with this roster.