I've noticed the same thing on PC. Metro; piss it by 1000 tickets and then go and play on the Gulf of Oman and lose by a thousand with the same teams. Also won handsomely on Metro only to lose the rematch by practically the same amount of tickets. On that map particularly; once you get in the ascendancy, it's hard to lose especially the other team to be pinned in their spawn unintentionally due to the way matches pan out. If you get on the backfoot early however, you're likely to be hammered.
Metro is just too chaotic most of the time and the fact it's only A to C on Conquest Large is a bit silly really. Gulf has a really weird layout and isn't very enthralling plus Firestorm is extremely horrible if you're up against recon campers down the stretch.
Haven't sampled Caspian yet but so far, I'm not sold on the SS maps and I didn't get into China Rising much either. The core maps seem a much better quality and more open meaning both teams have a balanced chance throughout to control the game at any given time.