The CAS2 is a kind of cognitive instrument as well, but with emphasis on different factors than the WISC. But yes, EF is extremely important to the real-life expression of cognitive-academic abilities. After all, it's the primary factor that separates successful from unsuccessful post-secondary students and working professionals. And yes, especially for math.
As to receptive vs expressive language: I do see it from time to time. I just had a couple of evals recently (not 2e) with students perceived as being severely cognitively impaired who actually had much higher verbal cognitive ability than teachers expected, but horrific listening comprehension. In the classroom, they generally present more like their receptive language than their expressive language--except when they suddenly surprise you. I would expect the inconsistencies to be even more marked in high cognitive students.
