The problem with Tanev is he is offensively (except for last night) mostly useless. He has never taken a shot that you cannot track from his stick towards the net as it drops to the ice before even getting there. Even if he stops 90% of scoring chances against, he participates in 0% of creating offensive chances. He is the defence equivalent of Jay Beagle. He is just not worth the cost of Toffoli's current contract.
It is irrelevant that he looks great in our end most of the time. He has way more opportunity to look great there, because that is where he always is when we notice him. Same as Beagle. He is rarely doing anything useful when the puck is out of our end. And he only once this year (a recent game) looked useful out of our end. A team of any combination of Tanev's and Beagle's and Erikisson's and Sutter's, which would exceed the cap, could well lose every game they played. Maybe 1-0 losses. But all losses. (Except for last night.)
The object of the game is to score more goals than the other guys, not to be really effective inside your own blue line and let somebody else worry about scoring.
If a defenceman cannot play offence at all, the max he should make is $2 million. If the player is a forward, that drops to the league minimum. You can always find guys with a motor who can't score. Tanev scores a game winner almost every 10 years, so I would be happy to pay him $3,000,000.
We pissed away at least 5 productive Sedin years because we had only 1 offensive line. The plan to shut the Canucks down was easy. Now with Toffoli, we have 2 actual offensive lines. Opposing coaches need to think who will cover our top 6 now, instead of loading up their top 5 against the only line that could threaten to score every shift. I guarantee you no opposing coaches have ever stayed up at night wondering how to neutralize Tanev.
People lining up to give Tanev the money Toffoli now gets and should continue to get (but he will ask for more and may get it somewhere else) should get in line to replace Benning, because they are drinking his Kool-Aid. You are not foundational (whatever the eff that means) because you block shots. What blocking a lot of shots means is you are in your own end way too much. Sutter by the way, several years and injuries (from blocking shots) later, remains the ONLY free agent forward in league history to get over $4 million AAV on a long term contract who never scored over 40 points in a year before (or after for that matter) getting the big money.
Having completed my rant, I agree Tanev is an NHL top 4 or 5 defenceman who any team in the league wouldbe pleased to have on their roster, even if only for the LTIR cap space. He is worth substantially more than the 6 Canucks forwards who are paid so much that our cap is screwed (Beagle, Sutter, Ferland, Errikkson, Rouselle, Baertschi, am I missing anyone?) but Toffoli is not one of them.