I still consider myself a Pogba fan and I would have been delighted to see him be a success here. However, whilst I definitely don't think he's been awful for five years, I also don't think he's had a single 'very good' season.
He has mostly only been 'very good' for short spells and those have generally coincided with the whole team being in good form. Given his talent and the fee which we paid (I think it is relevant), I expected there to be more matches in which Pogba made a decisive contribution, even when the team wasn't playing particularly well.
Perhaps those expectations were too high (I only watched him a handful of times for Juventus), but in my opinion, his time here has been a disappointment.