It used to be that buying a box gave you guaranteed ratios. This made it smarter to buy by the box, rather than by the pack.
Now, not only are the boxes just as random as the packs (which means it's the same chance to buy either) but this is the same for cases as well. Maybe distributors can get sealed items higher than a case, but as far as I know a case is the highest sealed product you can get.
Once you get out of sealed product, you don't get any more ratio guarantees.
Sure, Pokemon can change whatever they want, but it's bad business. The statistical value of packs have become super low.
Dark Explorers Pack $1.57
Emerging Powers Pack $1.49
Next Destinies Pack $1.24
Noble Victories Pack $0.73
Black White Pack $0.48
Add maybe $.50 - $.75 for the price of bulk commons/uncommons, but this is basically what packs are worth, based on statistical pull rates and secondary market card prices.
What this means is that unless you can get a pack of Dark Explorers for $1.57 or less, it's better to just buy the card that you're hoping to get in the pack off the secondary market.
While the change in box ratios probably doesn't affect these numbers, it does affect the reason that people buy boxes: To not get worse numbers than these.
Now, it no longer matters whether you buy a pack, a box, or a case. Your chances of getting something are still the same. The only reason it's better to buy in a box or case is for the bulk discount you get on the price.
It just doesn't make sense to buy packs anymore, in any form. Remember those numbers are statistical averages, meaning the packs you open could come out much much worse. They also could come out much better, but the chance is greater that they'll come out worse. Box ratios used to guarantee these averages, now it's all random.
The pack is dead to the smart player.