Anyway, Delpo played in 18 tournaments and he has 0 for Adelaide, so he still has only 17 countable tournaments. Shouldn't his "best 5th" countable result be 0 and not 5?
No because since he has 2 late withdrawals, the 0 is essentially mandatory
. It cannot be dropped, no matter how many tournaments he plays, until the second withdrawal drops off his rankings (I'm not entirely sure about the drop date for the 0, it may be from the first withdrawal).
In terms of the race, rather than the rankings, if you pick up a 0 for two withdrawals, you are stuck with it, and cannot replace it.