Why is “speed” a gray skill for DC players?

[Toxcatl]

So what you are saying is that if I have 2 players with a 120% average it doesn’t matter what their individual skills are?
So if I have a striker with 250% shooting and finishing and another one with 100% on both skills it won’t make a difference if both are 7 stars and 120% average?

Aha, it looks like this. There is no noticeable correlation between high skill(s) and player's performance. Maybe only the average of key skills for this position matters, who knows. So maybe there is a real, hidden, current quality of a player -- the average of his current position's key skills. And maybe it's something else, like, grey skills matter too, but with penalty multiplier.
We don't know.
Nik thinks individual skills don't matter. I was disagree, but now I think he's right. Even if skills have an effect, it doesn't visible on individual level.
The game mechanics seems to be very simple with huge random factor in play. TE is more like "strategy + slot machine" than "strategy + tactics". And by "strategy" I mean "farm greens and feed your players", nothing more.

If you buy a good young 18 yr old CB, and plan to keep him a few seasons, it’s worth training DL, or DR as that will make speed a highlighted attribute and ensure his speed stats don’t get warped down to 30% after a few seasons while his major stats are 150%+.

But if you keep playing him as DC only, why do you think it makes Speed useful? Set of key skills is determined by player's position only, so it is logical to assume that it doesn't matter if a player has a skill white or gray, if this skill is not a key skill for this position. In other words, Speed is not important for DC; therefore it doesn't matter how high player's Speed is, if he plays on DC position. Don't you think so?