Bryan Garner has written an interesting piece for the Student Lawyer on law student writing. I, like Garner, have encountered students who believe their writing has gotten worse since college. According to Garner, while students' writing may have gotten somewhat worse, most students never actually possessed good writing skills in the first place. This, says Garner, is because students have over-valued their writing abilities and, as a result, have failed to develop the skills they need to be accomplished persuasive writers (which is, after all, what much of legal writing is all about).
Garner's full article can be found here.