OK, so THIS ITEM 
puts me on tilt . Why? Well if your jungler buys it i feel like he fails 70-80% of the time and when the enemy buys it HOLY MOLY i swear they get sated in like 20 minutes even not fed. Like I understand the old devour needed buffs but DANG this is like a Feral Flare 2.0 .
Ergono2 votesWell using cheap math you're actually fairly spot on with your %, and you will come to realize that its balanced to an "extent" given other parameters we can loosely control for.
Here is why. Its a late game item that really can't tip the scales in your favor unless the match is fairly even or you are ahead. There is a 50/50 chance that the game relatively even to the point sated could turn the battle. There is a 25% chance that the enemy team is either way ahead or way behind. Sated really only effects that 25% you are already ahead. The 50/50 situation is such a large variable one team fight can make sated useless or not. If you are behind chances are you aren't getting stacks.
The issue becomes you have to make this choice early in the game where chances are you're in a 50/50 spot that can change at any moment. This is why high level pro play doesn't really value it because it lacks consistency. I would rather have an item that can capitalize of the 50/50 and push that advantage towards me. Your jg could get the kills in a team fight or they could be the first to go.
Chances are you witnessing your team being behind which makes their sated that much more salient. Next time see if you can spot this pattern in both directions. Especially competitive games that are dead even you will see how sated's vale shifts.
relaxedcactus1 votesSorry I was sarcastic a TAD too much. I joke a lot about "my team" vs "enemy team". I already learned how to deal with devour but like the damage is WOAH LOL. But thanks for the math it was interesting man.