Velocityshares 3X Inverse Natural Gas Etn (DGAZ)

[Braden09]

The market is currently trading in a 9.1 cent contango. July futures are more expensive than June futures contracts. Therefore, a short rolling a position from June to July can buy back June at a discount to where they sell July picking up a 9.1 cent bonus. While the shorts get a bonus, the longs have to pay to play.

Going forward the futures price seems to be mostly more expensive than its previous month. So the above exercise could be duplicated month after month
Or is that to simple ?