Hm. Clearly your DC is not an easy test-taker! That is quite a dramatic difference between the first and second administrations of VP. So right up front, we can pretty comfortably say that there is reason to view these cognitive results as possible low estimates.
That being said, he does have some patterns:
Verbal cognition is lower than nonverbal cognitions, which parallels reading achievement being lower than mathematics achievement on the WIAT-III. Of course, this is not fully consistent with his strong SBAC language scores (which is a mixture of reading comprehension and written expression measures). One factor is that the SBAC has a fair contribution from multiple choice item types, while the WIAT-III reading comprehension is entirely open-response and oral. This would be a commonality that connects to the WISC-V VCI tasks, which do require oral expressive language, and is also distinct from the SBAC, which does not.
Too bad the uni clinic didn't also give him the Arithmetic subtest. You could have derived an EFI (expanded FR), and a QRI (measure predictive of mathematical reasoning ability), which might (assuming he was sufficiently testable) have aligned better with his mathematics achievement data.
Another significant factor is that he may simply have become a whole lot more testable between the individual assessments and the SBAC, whether from the passage of time and increasing maturity, experience with practice SBACs in the school setting, or other causes. If he was having difficulty with testing, it would be more likely for someone suspected of being ASD (whether or not they technically meet criteria) to struggle with optimal performance on the cognitive than on the achievement, due to the relative familiarity of the tasks.
