Different WR’s work better in different systems.
None of the current WR’s were recruited to fit this system.
This system requires more precision in technique & mechanics in route running. The timing is a lot more of a focal point & the spacing is different, which means the onus to getting open & in your spot on time to catch the ball is more on the WR & not already baked into the system. The windows are tighter, therefore the propensity to drop the ball will be higher if you’re not already an Elite hands catcher to begin with.
Hence why the WR who has excelled the most thus far & has had the easiest transition was the best route runner, XR.
Between George, Brinson, K Smith & B Smith, it will take them some time to get more congruent with the Offense.