Players in these categories as mains, top performers in their class, will only get better. Data gathered from these players who have had to rely on basic mechanical skill and intelligence is valid, but it's skewed with each buff or kit change that's viable.
This means, to me, that every Mirage who was holding it down and playing him well before getting a more useful kit are now extremely valuable players. Good Lifeline players are simply good players. Bloodhounds that were talented for each buff have only gotten better.
It also means that metrics have to be reestablished, as far as performance curve measurements go. The top players as these mains become less relevant to judging overall Legend viability. Git gud has its drawbacks since now mediocre Mirage play is statistically more valuable than day 1 Mirage players.
"That's stupid", you say? Wellllllll if you take a good player who could perform well with a crap kit and use it to decide who's kit gets buffs then that good player skews the data to make that Legend look better than it is. On the other hand, middle of the road players who have to rely on a Legend's kit to survive tough fights are better suited to showing how Legend skills can change the way fights play out. A Mirage who made Mirage look great from the start, who is only getting better with a better kit, can make Mirage look A tier when he's B+ right now and made him look B tier from the start.