He's on the list because it's not a straight measure of his ability relative to his pick number, but relative to your pick position and overall draft class ability.

The formula is;

How the scores work

Higher is better

• Calculate % of games played, goals, and assists a player contributed to his draft class total
• Weight the percentage to account for position
• Average his games played, goals, and assists %s
• Multiply by 100000 to get the numerical score
• Subtract the average score of someone picked at the same draft position as him

Which is why in OP's top 10 list Jamie Benn ranks #1. Not because he's an exceptional player (though he is) but because his draft year is actually kind of crap relatively speaking. The average career point total for that draft year is 93 and games played is only 218. Only Kane has more points than Benn from that year, and only 7 other guys in the whole class are within 200 career points of him.

Johnson scores poorly because in the first round of his class alone 12 people have more career points than he does, the classes average career point total is 113 and games played is 264, and as a first overall pick he takes a larger hit in the formula with comparable.

I am surprised though that Hugh Jessiman doesn't have a worse score. He played 2 games in the NHL with 0 pts, was taken 12th overall, and was part of a stacked draft class. I would have thought he would have had a way worse score.