IIRC, Jacko's point last year was that his WHIP was not indicative of his ERA and that it (ERA) go up, without even looking at the specific rates (K/9, BB/9, etc.) and BABIP. In fact, I don't recall BABIP being in the conversation. The people that argued with him said, yes, it's true that the WHIP doesn't support the ERA, but rather than the ERA going up, the WHIP could come down. Which it did.
Now it appears he's shifting gears, admittedly to a valid point, because his original prediction, the only one we'll ever get BTW - ie that a Sox player will get worse (I know, shocking isn't it?), was wrong. So in order to maintain the only point he'll ever make, again - that a Sox player will get worse, he's fishing for another reason.
Personally, none of us know what's going to happen. You can't predict BABIP. And his rates were all over the board in different parts of the season last year. Whatever happens, happens, but there's equal room to argue either side, although none of it will be overwhelmingly convincing for this simple reason, he hasn't played in the bigs long enough to give you any idea of what to consistently expect from him.