I want to open this with
"I was probably the first person on CP to suggest Tarasenko money for Gaudreau, way back in October". So do not get me wrong. I value Gaudreau.
But there are a few issues you are brushing under the rug.
Players with a greater AAV than Tarasenko currently (all commentary is from the time of their signing):
Patrick Kane - 2 time cup champ, Conn Smythe
Jonathan Toews- 2 time cup champ, Conn Smythe, Selke, Center
Anze Kopitar - 2 time cup champ, Conn Smythe, Center
Alex Ovechkin - Rocket Richard, Art Ross, Hart etc
Evgeni Malkin - See Ovy + Add Center + Add Stanley Cup
P.K. Subban - Norris Trophy
Sidney Crosby - ... Sidney Crosby
Corey Perry - Hart Trophy, Rocket Richard
Steven Stamkos- Rocket Richard
Henrik Lundqvist - Henrik Lundqvist
Claude Giroux - Center, 3rd place Hart Finish
Ryan Getzlaf - Center, 2nd place Hart Finish
Jakub Voracek
Phil Kessel
Shea Weber - Defenseman
Rick Nash
Dustin Byfuglien- Defenseman
Ryan Suter- Defenseman
Zach Parise
Ryan O'Reilly - Center
Pavel Datsyuk - Selke, Stanley Cup etc center
Now I have bolded the players who are remotely comparable to Gaudreau. What is the common theme? They are overpaid. No Ifs and Or Buts. Those teams are
hamstrung by those contracts. Kessel is the sole exception - because Toronto retained 1.2M of his 8.0M cap hit (so for Pitt, he is a 6.8M winger which is fair competitive value). Yes even Patrick Kane is overpaid despite winning all of this year's trophies. The Blackhawks window probably closed the minute they had to trade away Patrick Sharp due to the new extensions Kane/Toews signed - both players are overpaid BTW not just Kane. There is exactly one winger in the league who is worth this kind of money and it's not even Ovechkin - it is Jamie Benn because he impacts the game like a centre.
If you are paying a player this kind of money they better be the best goalie in the world, one of the best two-way centres in the world, or one of the best defensemen in the world. Period. Else you are setting your team up to be uncompetitive. It's nothing wrong with Gaudreau but at his position he is unable to impact the game the amount he needs to be worth that pay.
Despite that, I understand that the market dictates value, not competitiveness. The Tarasenko deal is fair market value even if it is in all likelyhood going to be a handcuff. But that does not mean Gaudreau is a better player than Vladimir Tarasenko was when he signed his deal.
Prorating both players' final ELC seasons to an 82 game season here's why Tarasenko holds more value:
2014-15 Tarasenko vs 2015-16 Gaudreau
78 non 3v3 points vs 73 non 3v3 points
39 non 3v3 goals vs 28 non 3v3 goals
2.86 5vs5 Points per 60 vs 2.28 5vs5 Points per 60
0 3vs3 Points vs
8 3vs3 points(3G / 5A)
Now let's explore that last one.
3vs3...does that make a team more competitive in the playoffs? Answer honestly.
Probably not.
So what then is Gaudreau's value-added over Tarasenko? Increased likelyhood at winning a President's Trophy? Is a President's Trophy more valuable than a Stanley Cup?
You ask me, given the fact that Tarasenko scored 39% more goals (let's dock 5% from Gaudreau's AAV for that) and overall 7℅ more non 3-on-3 points (and let's dock another 7% from Gaudreau for that) but was one year older (let's add 5% to Gaudreau for that) with a 3.5% lower cap ceiling at the time, Gaudreau's real cap hit
should be ~7.25M (Or 58M over 8Y)
However for pride sake, you can give him a 7.575x8Y cap hit to show him we value him more than Tarasenko.
But to say he's worth a 7.8M cap hit for example, that means he's probably overpaid by $550k - that almost is an entire entry level or veteran minimum salary he would be overpaid by. Suddenly you've lost a roster player in terms of value subtracted.