This is theoretical nonsense. Give me clean statistical data of chance that a pick becomes long time 3rd liner/ top 4-5 D or better and than we are talking. This graph is just
It's actually a statistical model that measures the average success of each pick. Games played is generally the most weighted portion of the model (some players don't put up a ton of points, but generally if they play 500 games they should be considered an NHL caliber player).
Of course each model will assign slightly different values. In this particular model, the 90th overall pick is worth 1 unit. 200 is .1 unit. So you could make the argument that the 90th pick is 10 times more valuable than the 200th pick, and you'd technically be correct according to the model (on average), it's really counting penny's to a millionaire.
If you're more mathematically inclined the value of picks in the NHL and NBA decays exponentially. In the NFL it's a more linear decline, which is because talented players can be had across the entire draft, not just at the top.
For example, when the Sabres were about to draft Eichel Boston offered at least three first round picks in that years draft. They had picks 13,14, and 15 I believe. For a player of Eichels caliber (his expected value over his career) this trade wasn't even considered by Murray. In the NFL this trade would be graciously accepted by a majority of NFL GMs (if they're smart).
With that said, it's not really theoretical at all. People are using data to assign average career values of each pick. Outside of the top 40-50 picks, these values are so low it's insignificant. If you like a player for whatever reason, just take them. This is because however you slice it the value of pick 90 or pick 200 is fairly immaterial. Pick the player you like after the second round.