They should get the same amount of training.
Height has an effect on training speed, as does age.
There may be an effect based on other skills. The rules suggest that a player will improve skills related to others he already has faster.
And skills are actually real numbers. So a player might have a skill of 4.1 or 4.9 and be called "inept". When a player trains, his skill values increase, If it increased from 4.1 to 4.4 it would remain inept. If it increased from 4.9 to 5.2 it would become "mediocre" and have a green arrow.
The starter may have been closer to his initial pops.