Since the school appears to be concerned about him as well, there appears to be an opening to investigate further with the school, and perhaps try some interventions or accommodations. Did the school conduct any additional assessment, besides the WISC? Do you have achievement data? (Norm-referenced, like the WJ, WIAT, or KTEA; group, like the ITBS, MAP, SAT10; curriculum-based, like DIBELS, ORF, writing fluency probes). Has higher-level phonological processing been explicitly assessed on norm-referenced instruments? (CTOPP, CTOPP-2, PAL-II) What about direct executive functioning assessments? (DKEFS, NEPSY, CCPT, TOVA) Your school may or may not have access to this last category of assessments, in which case you will have to go outside, most likely to a neuropsych.
If I am reading your post correctly, he is functioning two years below grade level in writing skills and written expression. At this grade level, most schools would consider this a qualifying academic weakness in anyone of average or above cognitive ability. In an RTI school, this would certainly call for tier 2 (or sometimes 3) interventions, regardless of cognitive ability, and might result in an eligibility decision under dual discrepancy (below grade level/poor responder to intervention). In a PSW (pattern of strengths and weaknesses) or aptitude-achievement discrepancy school, this would most certainly qualify.
So basically, most models of LD identification would consider his situation, with written expression skills two grade levels below, as quite sufficient for eligibility.
