Behind those hyperlinked letters above, you will find a clinic in how to take an ill-chosen metaphor and belabor it into a limp mass of muddled logic and lusterless images. Thank you, Sam Tanenhaus.
Fortunately, he drops the metaphor by the second page, but the damage is already done. I think what happened is that he doesn't actually like Widows that much—who calls a book they like "predictably ingenious? Maybe he doesn't even like Witches much either, But Tanenhaus has a canyon-sized man-crush on Updike, so he wants to give him a superlative review, but therefore needs to tie the works that he likes—i.e. the things he talks about first—to the Eastwick books, making this awkward and forced metaphor of wizardry necessary.
But this is no excuse—in fact, it's an aggravation of the inherent awfulness of the original sin—ham-handed, clod-footed writing.