" By giving them an easy way start out without extending benefits for too long, they won't give up for getting only 0.001 dec for their wins. "

In my opinion it's not the point as this rewards increase very quick if you play and I think it's better to start low and come higher than to let a player win 25 DEC in EVERY of his first 100 matches and afterwards he will win less even in his won matches (and get only DEC if he win). In my opinion to add a pack or two is a better way and why not to add some potions ? Maybe also one mystery-potion, so that he see what he can buy with his DECs.