OpinionOPINION: Cabot and Cimerex buck recent trend in US shale patch with $7.4bn mergerMerger of companies with very different asset bases unique in recent yearsOld playbook: the late Aubrey McClendon believed in having assets in different regions. Cabot and Cimarex seem to be following his leadPhoto: REUTERS/SCANPIXMark PasswatersHouston