OK, just for fun, here is a list of the top 30 average fastball speeds for the year 2015, with their heights. This includes any pitcher who had 60 innings pitched or more, so obviously it brings in a lot of relievers:
Aroldis Chapman 6 4
Arquimedes Caminero 6 4
Trevor Rosenthal 6 2
Kelvin Herrera 5 10
Dellin Betances 6 8
Jumbo Diaz 6 4
Nathan Eovaldi 6 2
Noah Syndergaard 6 6
Ken Giles 6 2
Blake Treinen 6 5
Jeurys Familia 6 3
Tommy Hunter 6 3
Hector Rondon 6 3
Daniel Hudson 6 3
Jose Fernandez 6 2
Wade Davis 6 5
Garrett Richards 6 3
Yordano Ventura 6 0
Jeremy Jeffress 6 0
Roberto Osuna 6 2
Gerrit Cole 6 4
Joe Kelly 6 1
Luis Garcia 6 2
Stephen Strasburg 6 4
Fernando Rodney 5 11
Kevin Gausman 6 3
Matt Harvey 6 4
Carlos Martinez 6 0
Justin Wilson 6 2
Luis Severino 6 0
The average height of the top 10 is about 6-3. The average height of the top 30 is just a shade over 6-2.