"In a rough draft, we are rarely economical: We repeat ourselves, we belabor the obvious, we cushion our thoughts in excess language. ... Long sentences are not necessarily wordy, nor are short ...

Let me phrase that a bit differently: “What devices and methods do those who write use to create substandard, inelegant prose?” As the preceding sentence illustrates, bloated, wordy sentences produce ...

If there is a consistent mechanical or stylistic problem with the paper, rewrite a few of the student's sentences (change passive to active verbs, cross out redundant phrases, rewrite wordy sentences, ...