A particular emphasis of modern techniques seems to be cross-training, and by the start of season 17, we expect that just as improvement in one skill seems to be linked to related skills, now improvement in one skill will in addition be linked, more weakly, even to seemingly unrelated skills.
To me they're saying the elastic effect will now take other skills into account, albeit not as much as the ones already effecting the skill you chose to train.
So training a rebounding monster in rebounding, his training will be slowed down by additional skills now.
And training a player's weakness will be faster because more of his higher skills will be speeding up the weak one.
"Air is beautiful, yet you cannot see it. It's soft, yet you cannot touch it. Air is a little like my brain." - Jean-Claude Van Damme