Mid-sentence modifier

A mid-sentence modifier is a free modifier dropped into the middle of a sentence, usually between the subject and its verb, so the main statement is suspended while the addition is delivered.

Sanchez, who had signed the first report and regretted it since, read the second one twice. Subject, interruption, verb. The reader is holding Sanchez open across the whole insertion, and that holding is the effect: a mid-sentence modifier feels like a pause in speech, a qualification the speaker could not wait to add.

Used well, it is the most sophisticated of the three positions. It suits a fact that changes how the main verb should be read — you want the reader to know it before they get the action, but not so early that it becomes the subject of the sentence. It is also the natural home of parenthesis, where the interruption is the point.

Used badly, it is simply hard to read. The cost rises with length: a three-word insertion is a beat, a twenty-word insertion is a detour, and by the time the verb arrives the reader has lost who is doing it. The usual repair is to move the modifier to the front or the end, where it costs nothing.

One test. Read the sentence aloud. If you have to go back to find the verb, the insertion is too long, whatever the grammar says.