Why uniform sentence length is the loudest tell
Count the words in each sentence of a paragraph a model wrote, and they cluster — eighteen, twenty-two, nineteen, twenty-one. Human writing does not behave that way. A person writes a forty-word sentence that gets away from them, then a five-word one that lands, and the swing between them is what makes a page feel like someone is there.
The cause is mechanical. A model picks a likely next word at every step, and the likely continuation of a long formal clause is another long formal clause, so the output drifts towards the average of everything it was trained on. The average of a very large body of formal prose is formal prose with the edges sanded off.
Which is why swapping vocabulary never fixes it. Change utilise to use and delve to look at across a whole essay, and the sentences are still the same length, in the same order, carrying the same even weight. The reader cannot name what is wrong — they just stop trusting it.
What the rewrite actually changes in your draft
Four things change, in order. Long sentences are broken where a full stop can carry the join, and two short flat ones are merged where they were really saying a single thing. Stock connectives — moreover, furthermore, additionally, in conclusion, it is important to note — are deleted rather than replaced, because the sentence underneath almost never needed one.
Then the abstract nouns come back down. The implementation of the new policy resulted in a reduction in processing time carries three nominalisations and a verb doing no work at all; the new policy cut processing time says the same in five words. English hides its verbs inside nouns, and formal writing hides them deeper.
Last, the closing paragraph that restates the opening gets cut, or given something of its own to say. That paragraph is a habit of the form rather than a service to the reader, and a marker who has just read nine hundred words does not need eighty more summarising them. Tone is made uneven on purpose too, so one sentence in a paragraph carries more weight than the rest.
Why this will not beat an AI detector
This needs saying plainly, because plenty of tools selling the same thing will not say it. Detection software guesses, and it guesses badly in both directions. Text no model has touched gets flagged, machine-written text goes through clean, and the American Declaration of Independence has been returned as AI-generated by more than one well-known detector.
The false positives are not spread evenly, either. Writing by people who learned English as a second or third language is flagged far more often, because it tends towards simpler and more predictable word choice — which is close to what these tools measure. For an Indian student submitting in their third language, that is a real hazard, and no rewrite removes it.
So use this to make a draft read better, and for nothing else. It will not add a fact your draft does not contain, will not repair an argument that does not hold, and cannot make you able to defend the work in a viva. Rhythm is not substance. A well-paced empty paragraph is still empty.