Du Plessis had a long list of games where he consistently lost the tosses in all formats o the game. In tests suck toss losses were a joke in bad taste - he lost all three tosses making in 7 tests in a row where he lost the toss.
In the last five matches where De Kock was responsible for tossing the coin he won the toss 4 times out of 5 tosses made.
Because of the idea that the toss would have a 50:50 chance of being called correctly in his favour, the Du Plessis scenario was indeed mystifying. I could not understand how the opposing captains could get he calls correctly in their favour continuously - so I started looking carefully at why it happened.
What I did find out in looking carefully at the tosses I noticed two things in Du Plessis in making tosses and those were -
* that it is traditional that the captain making the toss show the opposing captain the coin before he made the toss and the opposing captain could see which side of the coin is on top; and
* that in the case of Du Plessis tossing the ball the coin did not go very high in the air and there was no spinning of the coin in the air.
That may have been the reason why the opposing captains were consistently able to call the toss in their favour, but when I remarked on that observation on site some members went on all-out attack. Mozart went ballistic as well.
I have watched the coin tossing of De Kock and noticed that the coin went higher in the air and in the process spun in the air and the captains calling the toss lost more calls than they won. It became a guess which side the coin would end up in.
All I could conclude is that in the case of the Du Plessis coin tosses the calling captains knew nearly all the time the way the tosses would end up as, while in the case of De Kock they did not,