So, I'll admit, when I saw Helm and $3.85 I thought, WOW, that's a lot, but it wasn't based on any real facts, just a gut reaction....perhaps it was out of date...guys are making more, etc. So I quickly checked the real numbers to see how your buckets match up. I think you've estimated pretty well, except the range you've given for 3rd liners seems way out of wack.
Here's what I came up with purely based on the top earners (forwards) for each team (1-3, 4-6, 7-9, etc.). The numbers here are the averages of all 30 teams. So, there is some holes you can poke (when did they sign, UFA vs. RFA, etc.), but I think this is the closest to reality you can do without spending too much time on it, since it really isn't worth it.
4th - $0.81 - $1.2M
3rd - $1.46 - $2.6M
2nd - $3.18 - $4.44M
1st - $5.09 - $7.14M
So, if everyone thinks Helm is a 3rd liner (which he is on DET based on ice time), then $3.85M looks like more than just a little overpaid. HOWEVER, some teams have better quality 3rd liners than others, warranting being paid more than the average....which I think is warranted for Helm, but I just think it's gone way further than what's warranted and then tack on the years and NTC that makes me go WOW!
No big deal, but it doesn't make me go WOW!
Edit: If I was really upset and felt strongly about it, which I'm not...no big deal to me, but if I was, I'd try to put in the time to come up with comparables....at his level of offsensive production + all the other intangibles, etc....try to see where he fits vs. other players in the league with similar attributes. Maybe you'd see that a $20M contract makes sense.