My goalkeeper is on his 12th season. He was a 12 token youth that someone sold me on auction as a 5 star with initial training speed of 40/80/105.

Years ..... Stars
18 ... 5 then 6
19 ... 5, SA, 6, 7
20 ... 6, 7
21 ... 6, 7
22 ... 6
23 ... 5, 6
24 ... 5, 6
25 ... 5, 6
26 ... 5
27 ... 4, 5
28 ... 4
29 ... 3, 4 - current speed 12/25/40

Now it will be
30 ... 3
31 ... 2
32 ... 1