Where to insert comma(s)?

Question

Compare these: > 1. She tried, and, as expected, failed. 2. She tried, and as expected, failed. 3. She tried and, as expected, failed. 4. She tried and as expected, failed. 5. She tried and (as expected) failed. The first seems most correct, while the last seems most elegant. Is it all a matter of taste/style? I'm also curious of these: > 6. She tried, and failed. 7. She tried and failed. Is there ever a need for the first form?

Answer 1

Look at it this way: "as expected" is a descriptive phrase that could be eliminated without substantially affecting the action-result information of "She tried and failed." As such, it is set off with commas by "She tried and, as expected, failed."