What I think - distracted with phone, then got shocked he was close to the divider. Over-corrected to the left but went to wet patch, lost traction on rear and hit the brakes and continued hitting the brakes while the car slide without trying to perform any correction whatsoever.

He should have let go of the brakes / hit the throttle to power through with counter steer instead of just praying for the brakes to stop him in time.