On the cognitive side:
He has exceptional working memory, both visual and auditory, meaningful and rote, topping out the scale. Processing speed (which is the area most affected by fine motor) is his weakest area, in the Average range. He actually shows better language reasoning than non-language reasoning. His visual spatial skills are actually solid to exceptionally strong, which isn't consistent with a visual processing deficit.
What is more suggestive of writing concerns is what we see in his KTEA, which is extremely strong in all reasoning and application skills (with the exception of written expression, which is in the upper end of the Average range). The areas of personal or general weakness are all centered on fluency skills, with a consistent pattern of relative weakness (in the lower half of the Average range) in rapid naming skills, which contribute to automaticity skills. (Rapid naming is also one of the three pillars of effective phonetic reading development, but since his other two are solid (phonological processing) to exceptionally strong (auditory working memory), this relative weakness doesn't appear to have affected his reading decoding skills in any way. That doesn't stop it from affecting writing/encoding skills.) Since written expression requires a host of automatic skills (letter formation, spelling, capitalization, punctuation, grammar) before you can even get to generating organized and meaningful language, it is not surprising that he should have some challenges with writing.
The very high Block Design score suggests that it is not visual processing that is the obstacle, but more likely automaticity, probably for skills like spelling and letter formation, at a guess. His untimed spelling is Average, which is functional, but far below his verbal cognition. Then you see writing fluency, which is Below Average (and this isn't even scored for accuracy--purely for the number of words generated), and also far below his written expression. His other pencil-and-paper fluency score (math) is much lower than his untimed basic skill score. See also the sizable gap between written and oral expression, which tells you that it's not language that's the issue (not that we thought it was, with those verbal cognitive scores), but the process of putting it to paper.
Has he been looked at by an OT? That's who you need to actually rule in/out fine motor issues.
I'd also be interested in some error analysis. Was his Writing Fluency score slow because of his actual rate of physically writing words, or because he kept stopping to correct spelling, or because he was slow to generate sentences, or because he got distracted, or something else? What kinds of errors did he make on Written Expression? Were they predominantly mechanical errors, or evenly distributed across grammatical, structural, and mechanical errors, or some other distribution? (Because if they were mostly mechanical (spelling, punctuation, capitalization, etc.), that would tend to support the idea that it's automatic skills that are his area of struggle in writing.) How is his writing if you have him try typing/keyboarding or speech-to-text?
