Yeah there are a few players who stand out as being picked pretty late relative to their performances. Going through it:
de Villers - very end of Round 2, averaging 68 with the bat and now also keeping
Bumrah - Round 4, averaging 22 with the ball
Maharaj - Round 4, averaging 24 with the ball
Amir - Round 4, averaging 24 with the ball
Shami - Round 4, averaging 19 with the ball
(to put these Round 4 picks into perspective, they actually all came in a row right after Ngidi and Herath had been picked)
Vijay - Round 6, spent most of the tournament in the top 5run scorers, averaging 55 now
Mominul - Round 6, averaging 59 with the bat
Ishant - Round 6, averaging 23 with the ball (I think it was still in the teens until a couple of rounds back)
Buttler - Round 7, averaging 56 with the bat and keeping
Yadav - Round 8, averaging 22 with the ball
Bracewell - Round 8, averaging 39 with the bat and 28 with the ball
Rohit - Round 9, averaging 50 with the bat
Haris Sohail - Round 10, averaging 54 with the bat
Wade - Round 13, averaging 42 with the bat and keeping
Rassie - Round 13, averaging 39 with the bat
Hafeez - Round 13, averaging 39 with the bat and 36 with the ball
Ballance - Round 14, averaging 38 with the bat
Morris - Round 15, averaging 30 with the bat and 29 with the ball
Hendricks - Round 15, averaging 30 with the ball
And the man, the myth, the legend:
Nick Larkin - Round 15, averaging 51 with the bat