I doubt the general sports watching public could put a face to more than two of these players.
The highest ranked group by far this year, but Ymer and Fokina have particularly built their resume with recent challenger trophies; six between them. Ruud has not been seen much on hard courts as well.
I just built my new hard court rankings (average of Recent Elo ranking and Hard Court points won ranking for 2019):
Name Hard Rank Average Elo Rank Points Rank
Rafael Nadal 1 2 1 2
Novak Djokovic 2 2 2 1
Roger Federer 3 3 3 3
Daniil Medvedev 4 4 4 4
Denis Shapovalov 5 10 9 11
Kevin Anderson 6 11 8 14
Alexander Zverev 7 12 10 13
Alex De Minaur 8 12 17 6
Dominic Thiem 9 12 5 19
Kei Nishikori 10 13 15 10
Stefanos Tsitsipas 11 13 6 20
Jo Wilfried Tsonga 12 14 13 15
Gael Monfils 13 14 21 7
Andrey Rublev 14 15 12 18
Diego Sebastian Schwartzman 15 16 19 12
Roberto Bautista Agut 16 16 22 9
Stan Wawrinka 17 17 11 22
Pablo Carreno Busta 18 17 16 17
Grigor Dimitrov 19 17 18 16
Milos Raonic 20 17 26 8
Matteo Berrettini 21 21 7 35
John Isner 22 22 23 21
David Goffin 23 23 14 31
Filip Krajinovic 24 26 27 25
Jan Lennard Struff 25 27 30 24
Nick Kyrgios 26 30 20 39
Andy Murray 27 31 32 29
Adrian Mannarino 28 34 34 33
Karen Khachanov 29 36 25 46
Hubert Hurkacz 30 37 38 36
Marin Cilic 31 38 28 47
Reilly Opelka 32 40 36 44
Tomas Berdych 33 40 52 28
Sam Querrey 34 42 29 54
Felix Auger Aliassime 35 43 37 48
Fernando Verdasco 36 43 55 30
Jeremy Chardy 37 43 31 55
Egor Gerasimov 38 44 54 34
Nikoloz Basilashvili 39 46 39 52
Miomir Kecmanovic 40 48 64 32
John Millman 41 49 47 50
Borna Coric 42 50 50 49
Daniel Evans 43 51 58 43
Jordan Thompson 44 51 59 42
Radu Albot 45 53 49 56
Fabio Fognini 46 54 24 84
Lucas Pouille 47 55 35 75
Aljaz Bedene 48 56 43 68
Ugo Humbert 49 56 66 45
Richard Gasquet 50 56 45 67
Taylor Harry Fritz 51 58 42 74
Yoshihito Nishioka 52 59 44 73
Steve Johnson 53 60 62 58
Frances Tiafoe 54 61 57 64
Guido Pella 55 61 41 81
Gilles Simon 56 61 63 59
Philipp Kohlschreiber 57 61 71 51
Jannik Sinner 58 64 89 38
Andreas Seppi 59 66 68 63
Christian Garin 60 67 46 88
Cameron Norrie 61 68 75 61
Marton Fucsovics 62 69 77 60
Mikhail Kukushkin 63 69 51 87
Kyle Edmund 64 69 56 82
Dominik Koepfer 65 72 72 71
Vasek Pospisil 66 73 80 65
Hyeon Chung 67 73 48 98
Benoit Paire 68 74 53 94
Joao Sousa 69 77 67 86
Roberto Carballes Baena 70 82 73 90
Leonardo Mayer 71 82 78 85
Alexei Popyrin 72 86 76 95
Gregoire Barrere 73 88 86 89
Ricardas Berankis 74 95 91 99
Only five players in my top 74 on hard courts (bolded above and Popyrin, a sixth, playing challenger this week.) Ymer and Fokina simply don't have enough points on hard courts at ATP level to make rankings. Ruud 65 for Recent Elo, but only 135 on points won.