It's not about what he can do that others can't do, it's about the degree to which he can do it against the degree that others can do it. Do the Stars bottom 6 do anything that say the Leafs or the Penguins or the Oilers don't do? Not really, no. The bottom 6 players on those teams are capable of blocking shots or marking opposing forwards or killing penalties. They just do those things less frequently and less efficiently. Dickinson has no unique skill, but he does the things he needs to do well. He can play any position, any line 2-4, and execute the system that the Stars play. I'm high on Caamano, I think with like 5-10 more pounds and just more defensive system training he could become a real good system player. Gardner and Tufte are they're promising, maybe slightly less agile than Dickinson, I think they'll be on the team someday in some capacity. And they need time to learn. Because defense is one of the more difficult aspects of the game to learn, because it's based on system rather than individual skill. It's not frequently the case that a kid on an ELC will be as good defensively as a veteran, and ELC's are so short that 2, 3 years later that kid is now also an RFA.
Don't need to look further than the other teams in the playoffs. Tampa pays 3C Yanni Gourde 5.2 mil. They traded a 1st round pick and Nolan Foote for bottom 6er Blake Coleman. They traded a 1st round pick for Barclay Goodrow. There's Cedric Paquette, who is significantly worse offensively than Dickinson despite being on a better offensive team. The Isles cap situation has been heavily discussed, but they're in the conference finals, they took Tampa to at least 6 games. They obviously paid big bucks to Cizikas, Clutterbuck, Komarov, Martin, and they traded prime picks for JG Pageau the 3C, like Gourde, also signed for 5 mil. Is it absolutely necessary? No. Sometimes you do get kids on the last year the ELC who can do all the functions and that's great. St. Louis won their cup last year with 4 of their bottom 6 players on their last year of ELC. All of them are getting paid much better now though. And I'm not suggesting that you throw Isles' type money at bottom 6 guys. But you shouldn't undervalue the bottom 6 either. The teams that are the most top-heavy teams in the league are out of the playoffs or didn't even make the playoffs.
Market value determines contracts. And maybe that rate isn't 2.5, maybe it's 2. He's not going to get any more or less than he deserves. Now if, say, Dallas was very successful. And teams started trying to copy-cat Dallas' style of hockey. And as a result the public perception of Dickinson rises and some team is willing to pay good assets for him, like the Blake Coleman deal, where when he signed his contract he was scoring less than Dickinson, but he improved his game and showed promise to be a solid upgrade to another team's bottom 6 and someone offered a first round pick and a top prospect. Or the Barclay Goodrow case in which Tampa felt he would also be a solid upgrade to their bottom 6 and their PK and they gave up a 1st for him. I'm not opposed to trading and replacing Dickinson.
But you have to get something for him. The bottom 6 is a very important part of the lineup. Dallas did not get to the Stanley Cup finals this year because of their top 6. Some bottom 6 players are better than other bottom 6 players just like some top 6 players are better than other top 6 players. Dickinson is a very good bottom 6 player, and for the foreseeable future a significant upgrade to other bottom 6 options. So I wouldn't just deal him for next to nothing in an attempt to cap dump. Because if the kid that replaces him scores a bit less, or gives up a few more goals, that could be the difference in a playoff round.