are you trying to suggest your analogy was intended merely to show it is possible to reject some players chances sometimes? because nobody was arguing it is never ever possible to dismiss a player's chances ever.
it seems to me you used an analogy to argue the degree to which you were dismissing the player was reasonable. given that context your analogy should have been analagous as to degree.
No. The analogy was intended to show that the more likely outcome should drive current perceptions, even if the unlikely outcome can turn out true.
The extreme case being someone taking a shot in the dark about a player that they couldn't possibly foresee being that good and nailing it. The fact that he was right and it was proven that anything can happen doesn't mean scrutiny over the assumption was never justified, because any leaning in that direction would have clearly been completely unfounded guesswork.
The non-extreme case would similarly be true, because the same logic applies, even if it isn't as clearly obvious as it was with the analogy. If it were possible to unambiguously determine that Player A is a sliver more probable to be better than Player B, you could not simply say "it's totally possible that player B will end up better, so I think he will." Even if the current difference between them is small, you would still need a compelling reason to conclude that the probability is actually reversed in order to reasonably favor player B. It would be wishful thinking to whatever small degree of that difference between them to suggest that Player B would be better or to dismiss someone who thinks Player A will be better.
Apply that to what we're talking about-- it makes sense to assume that Tkachuk will be better, given how probable it is based on what we currently know about where they are. There's nothing stopping Tkachuk from reaching his maximum potential, and he's almost there already, whereas Juolevi needs to overcome every unlikely hurdle that Tkachuk already has, every hurdle that he jumps in the future, and then some, in a significantly shortened window of time. It doesn't make sense to scoff at the assumption that he probably won't, and it certainly doesn't make sense to still lean towards thinking that Juolevi will be better anyways, despite the obvious giant lead one has over the other. The fact that it's very possible for Juolevi to reverse his fortunes doesn't justify optimism that he will. The fact that defensemen take longer to develop might give him a longer window for that to be a possibility, but it should do nothing to reasonably sway anybody towards thinking that he will, either. The significant degree that Tkachuk is currently better than Juolevi is equal to the unreasonable lengths that a fan would need to leap in order to doubt that Tkachuk will end up better or to imply that it's still up in the air.