RIP. One of the best defenders in his generation and a defensive titan who deserves to be viewed in the same light as Big Ben/Mutombo/Draymond/Gobert.
To expand on this, the Jazz defences he led during his prime (roughly '85 to '89) were fantastic - they finished with rDRTGs of -4.5, -2.6, -4.6, -4.9 and -6.3 during that timespan (-4 is in the upper stratosphere historically while -6 is on the edge of an all-time great one), finishing 1st in team DRTG every year besides the '86 season (3rd).
As he aged, the Jazz fell back to earth defensively and never reached those heights again despite stocking up on defensive big men to pair with Malone in the frontcourt for the remainder of the 90s. He also comes out pretty decently in adjusted +/- studies despite his short prime hurting him in these attempts to approximate his impact - he has a good-but-not-great result in this
data triangulation attempt that used considerable data from his post-prime years, which suggests that he might have truly had superstar impact during his prime as a defensive anchor.