I for one would leave the calibre system out , put in a plain 5 star rating on each player but if the calibre system is kept and i think it will , then as Bakkiesbokke said let it change during the course of the players career , mayby in the colts all the players are amateur as this is still school rugby for fun , when they go to acadamy it goes to professional , then if they play say super rugby it goes to national and then play for their country international , then players that get 20 MOTM awards becomes world class
But also , when the player get promoted , they stay the same calibre until they played 10 games in the higher class matches , this will be great because a player that is promoted is nervous in his first games so his calibre stays the same then is changes after 10 games because he now is use to it , will be nice feature .
When a player is injured or does not play for a few weeks his calibre starts dropping and also as bakkiesbokke said when a player get old the calbre drops agian until the player retires