Master of None - I don't know of a computer program that can analyze writing for the issues you described, but there are diagnostic tests that can give you some of that data. Test of written language (TOWL) is used widely by neuropsychologists and learning specialists. There is as subtest within the WIAT that includes a writing prompt. Some schools use the Woodcock Johnson - but these subtests are usually much too brief to pick up problems - especially at the older grades.

Here are two links to help with your research:

Testing Written Expression http://www.wrightslaw.com/info/test.written.lang.htm
Writing tests: http://concordspedpac.org/TypesTests.html#Writing


You ask if advanced language arts classes would be appropriate for him. It depends - how far off is his writing? Would he be allowed accommodations such as a laptop and more time? Do accommodations make a difference and help to level the playing field? Could he do it with the help of a tutor (this is what I've done for my HS daughter). What is his frustration tolerance? Confidence level, energy level? Are there other issues that would also get in the way such as attention and organization, spelling troubles, expressive language issues?

Finally - my experience was that honors level courses assume HS level writing skills. There is little or no instruction on writing skills, beyond basic peer editing. In our school system the honors courses concentrated more on the reading and analysis of literature and assumed that the student could respond fluently and eloquently in writing. My daughter's writing skills actually slid as a result of 2 years in Middle School Honors English. We finally got her a tutor that reviewed the basics and taught her higher level writing skills.