The EIA (US) and German statistics show that, in aggregate, wind-energy sources produce a relatively steady amount of power. Individual turbines and even whole wind farms might not be deterministic, but all the wind farms taken together... are.
In the real world, they're not. Here's the current CAISO output graph for all of California (which is 800 miles long and has a wide range of climate zones, with wind farms hundreds of miles apart) in the last 24 hours. Max wind generation today: 3600MW. Min: 300MW. That's over a 10:1 ratio. Checking PJM (the power grid for the northeastern US), today's max was 3200MW. Min: 900MW. About 3.5:1. Most days, those ratios are around 4:1.
So you still need a lot of natural gas plants that can be started up when the wind fails. Understand that load varies about 3:1 over the course of a day, in a predictable way, with peak load in midafternoon.
Solar power output matches air conditioning load very nicely. Wind, not so much.
The price of bulk power goes way down late at night. Once in a while it goes negative for an hour or two. This happens on PJM when load is low, Ontario Hydro has excess water they're running through generators, the nuclear plants are running smoothly and don't want to shut down, and the wind turbines are getting good wind. The hydro and nuclear guys have a slow response time, so they'll pay to generate power rather than shut down for a few hours. So the wind guys, who can stop in a minute or two, drop out rather than pay. The turbine blades go to zero pitch and feather, the brakes come on, and the turbines slow and stop.