Overwatch is an ever-changing game and matches will have their own ebb and flow as players fight around objectives. Every map has certain chokepoints where both sides tend to clash and attempt to take map control. On a map like Ilios, it can be dangerous around the edges of the map or the large hole in the middle.
Characters with a knock back thrive here and that would include the hamster.
Redditor AreYouHigh2 was using Wrecking Ball and had a rather simple plan. Grapple onto one of the nearby buildings, and stop swinging around like a YoYo until the enemy team is defeated, knocked off the map, or retreats.
Not a bad idea, and as you can see, it works. Hammond continued to spin in that pattern, and every time he came back around, another enemy player was either killed or knock off the map.
And it's even more difficult for the enemy team to try to focus on the Wrecking Ball when the enemy team is right in their face. This is when you just tuck tail and run.