It is unfortunate that those percentages mean absolutely nothing for the average player, since they do not apply to any one account. That is a percentage which applies to the playing community at large over who knows how long, but it serves to disappoint many who feel they do not meet it or gives some reason to brag when they get 10 legos in 100 shards, etc.
I try to stay calm by ignoring any odds I see whatsoever.
as far as freedbies given by the game, those shards have the same problem with zip, nada, zilch getting anything good. The free champs are usually mediocre to poor, maybe one or two exceptions. All those shards that turn out to be junk you still have to shell out lots of silver.
It is a casino mentality, there are screams of delight at some tables and slot machines, and a bunch of folks that go home poorer and disappointed trusting in "odds".