The Tigers led by as much as 34 points halfway through the third term as they went on to dominate centre clearances 16-5 and contested ball 149-120, leaving Kingsley to concede "we didn't deserve to win that game".
The return of Dion Prestia for his first game of the season after being sidelined with an Achilles injury helped the Tigers take charge of the stoppages, while former Giants Jacob Hopper and Tim Taranto were also influential.
But the narrow defeat is the third in a row where the Tigers have paid the price for one poor quarter while they also suffered from wayward kicking for goal when on top in the second and third terms.
"That is deflating. I feel we've almost got a split personality in the rooms at the moment," Tigers coach Adem Yze said.
"I'm so proud of our effort, so proud of our start, and to be fair, so proud of every quarter really. The last quarter got away from us a little bit, but it wasn't method, it wasn't system, it was just slight role execution.
"Their good players played really well in the last quarter and they just finished their work."
https://www.afl.com.au/news/1332533/career-ending-fears-for-gws-giants-veteran-callan-ward-after-knee-injury