gnar is an off meta pick and thats why you wont see him much in high elo the only reason that he isnt getting any buff is that he has a high playrate at LCS only and riot thinks that if the best of the best pick him he is in meta

Gnar is a pick that has everything that a pro top laner needs escapes engages cc ranged abilities to lanebully and outtrade someone thats why he is so safe and why pro players pick him in LCS

*tips*
prefer to auto enemy really hard with W instead of running behind throwing q and poking etc W is ur key ability when ur Small .

Hold ur E No matter what its your only escape and it has a big cooldown use it when you have wards at bushes and use it correctly at minions or at enemy dont use it on the ground like noobs do, it slows your enemy and it also puts a W stack on him and gives you attack speed which is really good.

preffered small gnar fight: E>Q>AA>AA>AA>Q>AA>....

Your Ultimate has a small cooldown since riot finally buffed it cooldown was insane jesus bad memmories now you can use it whenever u have the oportunity to sometimes after level 11 i use it to farm

Prefered use of ultimate in teamfights
farm minions and full ur bar to get big then E on last minion and flash on enemy and R

To win a teamfight 100% you need flash without flash your R is kinda useless

try to zone enemy when u are small and hope for a good R