Not sure if that was in reference to 2017, but if so, there's major value in Parker taking the opponents best CB on the majority of the plays when your QB cant throw the ball beyond 10 yards at an NFL level... And you cant blame him for the poor year for that same very reason...
I just don't see the value in taking on the opponents best CB if your not also winning those matchups consistently which he didn't.
I think about it in terms of basketball...if your the best offensive player on the team and attract the opponents best defender but can't win those matchups consistently than how good are you really? Sure when you face an all defensive team perimeter defender it's understandable to have a bad game but it's not like every team has 1st team all defensive team on their roster. Same for Parker he should at least feast on the lesser CB's, even if they are their teams best CB not every team has a top 10 CB.
When I see 2 other WR's on our team have pretty good years considering they had the same QB it makes me suspicious. When Kenny Stills has 14 20+ yard receptions to Parker who had 9 despite as you said Parker running deeper routes than any other WR it makes me suspicious.
When Stills catches 42.5% of passes 16+ yards deep compared to Parker who caught 30% of passes 16+ yards deep and even Landry who caught 33.3% of passes 16+ yards deep it makes power what brain is ponderin, though admittedly his opportunities were significantly less than Parker and Stills.