The Queen buff has thrown off Terran early pressure timings, meaning hellion harass and marine pushes are less threatening than normal. Less early threat means more drones, faster upgrades, and faster tech.

More queens in play means more creep spread and faster creep spread. You can cover the map in about 5 minutes if unchecked. More scouting means less threat.

The Infestor/Brood Lord army has been around a while. I don't think that's had any effect upon Zerg's win rate. In fact, I think the metagame is shifting away from such an imobile army. I'm wanting to see some more tricks like Ultra/Hydra.