I always rate Lewis, but he’s mentally talked himself out of driving this year’s Merc much like Vettel did at the start of the hybrid era.
I'm not sure he has. There might be an element of that (if i was him i'd still feel utterly demoralised at the end of last season but i have no doubt he's a much more mentally strong person than i am!), but in terms of head to head with Russell, he's ahead in qualifying and would be ahead in races if not for safety car's always landing for Russell and against him.
Russell is supposedly pegged as possibly one of the next greats, so it doesn't surprise me that he's close to Lewis in terms of talent. Merc clearly bought Russell in as Lewis' long term replacement I think.