Welcome!
In addition to Platypus's wise advice, I will suggest another category of reading difficulty. It may be that your DC has sufficient phonological processing to decode (hence the strong scores in phonetic decoding and word calling), but lacks automaticity. It is not a bad idea to check that the phonological processing skills are there, such as through a program like AAR (my personal favorite), or similar Orton-Gillingham-based programs like Logic of English (which was designed originally for older learners, so is a little less cutesy). Both are much more affordable than certified OG, Barton, or Lindamood-Bell, and attack essentially the same skills.
However, it may be that building automaticity separately will be where the focus of intervention falls. For that, I would suggest the evidence-based reading fluency program called HELPS
http://www.helpsprogram.org/, which takes about 20 minutes per session, with 3-5 sessions per week a reasonable dosage. This is also very affordable (free, if you download it all, and low-cost, if you order the printed materials).
Reading fluency is quite important for reading comprehension for most readers, and there is a notable gap between your DC's word-level decoding skills and fluency. Fluency affects comprehension principally in two ways:
1) Effortful, non-automatic reading leaves fewer cognitive resources for comprehension in general;
2) Slow pace creates additional challenges for making inferences, as content needs to be held in working memory much longer in order to make connections between related elements in the text.
Also, his accuracy falls quite a bit in connected text. Did you get rate percentiles for the WIAT-III Word Reading and Pseudoword Decoding scores, by any chance? That would tell us a bit about whether it's really a question of efficient word calling at the word level, or if we need to look for something else in connected text, such as poor scanning across the lines, poor self-monitoring (such as occurs in students with attention problems or impulsivity--also part of the differential diagnosis with CAPD), etc.
Actually, inattention also affects comprehension, especially #2 above, regarding inference. So in addition to possibly further investigating CAPD, looking at ADHD might also be in order.
And, FWIW:
"The phrase "unexpected academic underachievement" is often cited as the defining characteristic of specific learning disorder in that the specific learning disabilities are not part of a more general learning difficulty as manifested in intellectual disability or global developmental delay. Specific learning disorder may also occur in individuals identified as intellectually "gifted." These individuals may be able to sustain apparently adequate academic functioning by using compensatory strategies, extraordinarily high effort, or support, until the learning demands or assessment procedures (e.g., timed tests) pose barriers to their demonstrating their learning or accomplishing required tasks."
(DSM-V, Specific Learning Disorder, Diagnostic Features, para 5, p. 69)
