Backlund's ES production is consistent with his usual pace (currently at 31 ES points in 74 games). By comparison, he has the same ES production as Bergeron and Granlund.
The difference from his usual 40-55 pt production is due to the PP. Sutter relies heavily on the first PP unit, which is on the ice 80-90% of the time. The last season that Backlund had less ATOI on the PP was 2012-13. The Flames' second unit is also pretty weak, as it usually consists of Backlund, one of Mangiapane/Toffoli (whoever isn't playing on the first unit that night), and one of Hanifin/Kylington.
It shouldn't be any surprise that his production is lower than usual this season, given that he has limited offensive opportunities while continuing to face the hardest defensive match-ups.
There is no reason for the Flames to trade Backlund. Whoever takes his place (i.e. Dube, Ruzicka, Monahan, Carpenter) is a clear downgrade and will be badly exposed