Barkov is still playing, so it’s not fair to compare him to player like Bergeron defensively. He have not reached that level of dominance yet. He is far above Kopitar for sure. Maybe tier below Bergeron and Datsyuk, with a chance to reach that tier but not above that. He needs to dominate his peers defensively year after year for the next 5-8 years to reach that tier. Possible? Yeah for sure, he dominated his peers this year, but it’s far from easy. He is overall better player compared to Bergeron, but needs to prove more to be called Datsyuk tier overall player. It’s possible, but far from certain.
I believe there is plenty of posters who overrate and underrate him. As for now he should be rated in between. If he wins the cup and Conn Smythe, he should be rated higher.