World class means you play to an elite level standard on a consistent basis.
Very few deserve this label, only Messi and Ronaldo. I wouldnt even put Neymar, Bale, Griezmann or Mpabbe at world class level, let alone Paul Pogba.
If we are basing Pogba on his performances for us, he's in the "decent category". He has good moments in games, some flashes of brilliance and some eye catching passes on occasion. But nowhere near regular or consistently enough to be considered top class. He's nowhere near as good or consistent as some midfielders in the premiership, let alone the world.
World class players perform regardless of the quality around them and lead by example, instead of blaming "crap managers and a shite team" Just lazy excuses blaming other factors other than the player himself. Only Pogba is responsible for the level of effort and commitment he puts into his performances for us, and over the time period he's been here there is no way you can class him world class. You can call him talented and gifted by all means.
If you consider how good he can be with his skillset and physical attributes, how hard he works to achieve that, to put in the best display he can week in, week out you'd have to say he's majorly underachieved with us.