You CANNOT deduct commuting expenses. The only time you can deduct expenses for commuting is if you get temporarily assigned duty involuntarily outside of your tax home and you reasonably expect that it will last less than a year. You can then deduct the expenses for a year. After that, the IRS says it is no longer temporary and expects you to move and will not allow any deductions for commuting. Any good tax guy will tell you this and it is not really a grey area.
About the only thing you can deduct is parking costs if Delta won't pay for them. (I commuted from Houston and had to pay for parking and that could be deducted).
The stupid thing about it is if you live in say IAH and are based in ATL and can bid trips so that every layover is in IAH, you can deduct meals and incidentals for all of your layovers in the city you live in. That's how stupid the IRS rules are.