latecomer asked: I'm asking for examples of athletes that bloomed late to make their first team in their late 20s.
I don't have data on "making their first team," but I do have data on medalists.
the average age at which male athletes earn their FIRST medal in international tournaments is in their mid to late twenties. the precise figures are shown in the following table:
average age at first medal - men
event / mean / values
400m 23.44 (n = 177, sd = 1.84)
800m 23.78 (n = 166, sd = 2.33)
1500m 24.42 (n = 153, sd = 2.23)
5000m 25.01 (n = 116, sd = 2.73)
10,000m 25.83 (n = 145, sd = 3.02)
this table says that of 153 medalists surveyed at the 1500m, their average age at first medal was 24.42 years, and the standard deviation was 2.23 years, which means that the "normal" range is 22.19 - 26.65 years.
the oldest medalist at each of the middle distance events is as follows:
400m Mark Kiprotich Mutai (KEN) 32 years, 200 days
800m Osmar Barbosa dos Santos (BRA) 35 years, 138 days
1500m Mike Boit (KEN) 33 years, 276 days
3000m Bernard Lagat (USA) 35 years, 92 days
5000m Miruts Yifter (ETH) 36 years, 78 days
10,000m Dieter Baumann (GER) 37 years, 179 days
examples of athletes who won their first medal at greater than average age:
(note: I have excluded sub-saharan Africans, so that you have something to "relate" to)
800m - age limit 25 years
fname / sname / code / age
Johnny Gray USA 32.1288
Albert Hill ENG 31.4000
Erik Byléhn SWE 30.5425
Roger Moens BEL 30.3534
Nick Symmonds USA 29.6192
Marcel Hansenne FRA 29.5808
Noel Clough AUS 29.2877
Willi Wülbeck FRG 28.6411
Arthur Wint JAM 28.1890
Rick Wohlhuter USA 27.5863
Frank Handley ENG 27.2849
Paul Schmidt FRG 27.0329
Rich Kenah USA 27.0110
Philip Edwards BGU 26.8822
Tony Blue AUS 26.8082
Rune Gustafsson SWE 26.7288
Heinz Ulzheimer FRG 26.5671
Bram Som NED 26.4767
Piotr Piekarski POL 26.3863
Ben Cayenne TRI 26.3425
Alfred Tysoe ENG 26.3205
Jorma Harkonen FIN 26.3123
José Luíz Barbosa BRA 26.2658
Hans-Peter Ferner FRG 26.2575
Tomás de Teresa ESP 25.9397
Bevil Rudd RSA 25.8658
Gary Reed CAN 25.8548
Luciano Sušanj YUG 25.8164
Earl Eby USA 25.7452
Achraf Tadili CAN 25.7041
Alberto Juantorena CUB 25.6411
Audun Boysen NOR 25.3014
Seymour Newman JAM 25.2384
David Hall USA 25.2082
Hermann Engelhard GER 25.1096
Lukáš Vydra CZE 25.0000
1500m - age limit 25 years
fname / sname / code / age
Driss Maazouzi FRA 31.8247
István Rózsavölgyi HUN 31.4384
Johan Cronje RSA 31.3479
Philip Noel-Baker ENG 30.7973
José Luis González ESP 29.7452
Carsten Schlangen GER 29.5781
Charles Bennett ENG 29.5452
Mahiédine Mekhissi-Benabbad FRA 29.4247
Mário Silva POR 29.1096
Eino Purje FIN 28.4493
Peter O'Donoghue NZL 28.3425
John Whetton ENG 28.0384
Juan Carlos Higuero ESP 28.0164
Leonel Manzano USA 27.9014
Arturo Casado ESP 27.5068
Jim Spivey USA 27.5014
Francesco Arese ITA 27.3397
Steve Scott USA 27.2767
Terence Sullivan RHO 27.2329
Manuel Olmedo ESP 27.2027
Branko Zorko CRO 27.1068
Han Kulker NED 27.0438
William Whyte AUS 27.0192
Glenn Cunningham USA 27.0055
Anthony Whiteman ENG 26.8548
Jürgen Straub GDR 26.7425
Adil Kaouch MAR 26.6055
Henry Eriksson SWE 26.5863
Tom Birger Hansen DEN 26.5342
Gunnar Nielsen DEN 26.4301
Youssef Saad Kamel BRN 26.3918
Erik Jørgensen DEN 26.3452
Alan Simpson ENG 26.2274
Alan Simpson ENG 26.2274
Joseph Mostert BEL 26.1123
Josef Odložil TCH 25.9425
David Campbell CAN 25.9205
Eamonn Coghlan IRL 25.7836
Miklós Szabó (1908) HUN 25.7534
Henri Deloge FRA 25.6466
Dan Waern SWE 25.6000
Lawrence Shields USA 25.4575
Hauke Fuhlbrügge GER 25.4493
William Nankeville ENG 25.4274
Abdelaati Iguider MAR 25.3699
David Moorcroft ENG 25.3397
Henryk Szordykowski POL 25.2986
Josy Barthel LUX 25.2548
Jens-Peter Herold GER 25.2493
Lennart Strand SWE 25.2000
Gerald Backhouse AUS 25.1863
Rashid Ramzi BRN 25.0658
cheers