Training speed depends on their value.

For example (I have no idea what the value of players are at this level, so I am making up numbers)

If
1) a 24 years old striker with 97 quality; 45 M value
2) a 27 years old striker with 98 quality; 30 M value

go with #1; soon, he will be as good as #2


If
1) a 24 years old striker with 97 quality; 40 M value
2) a 27 years old striker with 98 quality; 40 M value

Go with #2 since they will train at about the same speed

If
1) a 24 years old striker with 97 quality; 40 M value
2) a 27 years old striker with 98 quality; 50 M value

go with #2 since he will train faster than #1.