His calling is inconsistent. Sometimes he's explosive, sometimes he's too damn slow, especially on weaker maps. There are maps that I simply don't like how he calls. For instance:
T-Side Overpass: On a map such a big map, you need to shrink it before executing. NAVI usually takes connector and then does nothing for a full minute. Watch Nafany play, he likes to go deep in bathrooms and gain info for example.
CT-side Inferno: Waaaaay too passive for my liking. Not enough banana control, not enough Info plays. Inferno is a map that has evolved a lot over the years to the point that at the pro level, it's become slightly T-sided. That's why some aggression and a lot of info is required to avoid the constant rotation. Watch gla1ve for this.
In a nutshell, Nafany is also a slow-paced IGL but he is heavily reliant on making info plays so that when he executes very late round, there are fewer odds of running into a stack. Not for nothing was Gambit's style referred to as a better version of NAVI earlier in the year.