I had to run before the end of that game, but I could see how DK was messing up. They would push, lose the bear, then leave the lane completely.
I think they should have just camped outside the base in a lane and constantly let creeps push it in. They could have forced IG to either come out to fight them, let the creeps slowly destroy the tower / racks, or find them in a favorable position for a blink / hole initiation. Or split push with a LD and a support top, with the other 3 bottom. IG would be forced to either commit 3 at LD or lose a fight there, opening up the bottom rax for DK.
They had a single lane rax'd, but if they had gotten a 2nd, especially with Aegis, IG couldn't fight them.