I'mnot familiar with the DAS II, but my guess would be that the dip in processing speed and the dip in matrices is related, perhaps to fine motor speed. If you can find a chart that shows type of prompt and type of response then sort the subtests based on each you might find a meaningful correlation.

polarbear

ps - just curious what prompted the second look at scores - is there something going on at school that's a concern or question?