having played both games as a front rower, I can tell you it is of course learnable.
The difference is while you are learning you drop your effectiveness you had in the other code until you catch up.
Doesn't mean a great player at one game will be great at the other.
If Sam played in the forwards he'd be a great 7 or 8. The problem is he is playing against people who have been doing that since they were 5 so he will miss some things.
It's a mistake to think rugby union is not learnable. Of course it is. It is just a case of what you learn when.
Right now, SB needs to learn how to ruck and how to lay the ball back when tackled. It's not hard, it's just different.
He needs to learn patterns in defence and attacking lines. He'll pick that up in a day.
If he moved to the forwards he will be an average scrummager and line out man until he gains the experience. At this stage I just don't think it is worth it.
I'd rather pick parts of the game that he will excel at, and put him there.
The no.8 often stands deep to take a long kick down field. I'd have a plan to swap him out so that he is stood there to take a ball, not unlike a RL kick off. He then gets chance to smash the line, at which he excels.
I would make sure he doesn't get caught in the forwards maul, as this takes him out of the attack and will wear him out.
For all we in RL like to scoff at the RU forwards, they are incredibly strong and weigh more than Sam. He will be able to use his impcat and speed to beat them but smashing into the forwards may be a mistake.
To me it's like saying a skier can't learn to snow board. If you have good balance and can handle the speed, you can learn, it's just different.
And in the opposite way, a boxer is big and tough but put him in the ring with a wrestler he needs to use his speed not his strength, otherwise he will just be flattened, in a non entertaining kind of way but an effective way.
