They're not the same age,and I'm not that sure if the one with JS 12 JR5 was clearly under the cap,but I think he was,cause the speed of other trainings was "normal"
he had 90+ skill points with 8 potencial,as you see my sample is really small and looking at it now its possible that OD has some effect,but still I'm skeptical about it
hope other people share they're observations too,and regarding the JR training for big man,its indeed painfully slow