The majority of silver junglers only cs 3 to 4 per min.
I swear that in most games I go on my smurf, the enemy jungler literally allows me to go freely in their jung, and lets me free farm in theirs from 3 mins in the game. They do not know that starting from raptors is the meta strategy, or that a sloppy gank will risk the other jungler gaining near a 200 gold lead every time.
I suggest that silver junglers should ward the jungle entrances more often, and concentrate on infiltrating the enemy to get a lead, rather than ganks. The more you secure camps and ward, the more the enemy jungler will be controlled by your own hand. This is a strategy game after all.