Delta is obviously trying to set a standard as to the amount of revenue each Medallion tier is generating. To that end, why not dump the BIS requirement and only use revenue as the yardstick? If DL wants $12,500 in revenue for a flyer to become Diamond, why should it matter if that money comes from two round trip TPAC BusinessElite tickets vs. 125,000 miles of hub captive shorthops? That's what I'm confused about...

Or why not make make it an either/or with qualifying miles vs. qualifying dollars. Reward high value flyers as well as the high mileage flyers:

Silver: 25,000 PQM's or 30 PQS'es or $5,000 PQD's
Gold: 50,000 PQM's or 60 PQS'es or $10,000 PQD's
Platinum: 75,000 PQM's or 90 PQS'es or $15,000 PQD's
Chairman's: 100,000 PQM's or 120 PQS'es or $20,000 PQD's