Starts in Formula 1 can be influential in determining how someone's race is going to unfold. When nailed perfectly, you are able to make up several positions - as the Ferraris did in Hungry and the Williams in Silverstone both at the expense of Mercedes.
For a perfect start, the driver has to release a clutch which then delivers torque for when the they set off. Throughout the weekend of any race, engineers calculate how much grip there actually is on the grid, so that they can set the right amount of torque in order to deliver 'The Perfect Start'. Now if they get it wrong and the car has too much torque, then the wheels will spin up or if they have too little torque, then they will just be slow off the line.
There are 2 clutches, the first one is fully open and the other one is partially closed. The two clutches are adjusted so that the car can perform the best start possible. All what has changed in the rules, is that the driver can no longer have any advice from the pitwall on what adjustments to make to the two clutches. So it could be too open or too closed, it is now up to the driver to decide from when he does the formation lap prior to the race and all the engineers can do is watch whilst the cars line up.
The start procedure itself hasn't changed, it's merely now down to the driver's own judgement to perform the best start.