Gaborik was traded at a younger age.
Nash is coming off just as bad of a year that Gaborik was in.
Nash at 7.8 is overpaid. He's probably worth around 6 if he rebounds, and if he produces like last season, then he is an anchor on the cap.
Gaborik was a year younger, which is marginal, but he was MUCH more injured, so the odds of him collapsing were spectacularly higher.
Nash's year is nowhere near as bad. He had to deal with nagging injuries reducing his offensive numbers, but they were still a bit better than Gaborik's, and more importantly, Nash is massively better all-around. When Gaborik didn't score, he was totally useless. When Nash didn't score, he was still one of the top contributors to the game.
There's no reasonable way to conclude that Nash is worth $6 unless you're clueless about his game. $6 is what a second liner gets. Dubinsky, who was traded (along with Anisimov and #1) for Nash just signed about a $6 contract (for a much longer term) and he's not qualified to shine Nash's shoes: smaller, worse defensively, nowhere near as good offensively. Dubi's career high is 54 points. Nash's career-worst season is still better than Dubi's average career season.
Look at the Isles giving Andrew Ladd almost $6 on a 7(!) year term after his 34-point season. Ladd is smaller, worse defensively, had fewer points last year and far fewer points in his career. A whole bunch of other second liners of similar or older age than Nash received $6+. Not one of them was as good as Nash. If he hit the UFA market, he'd get more than $6, probably about what he is making now, except he'd get a full 7 year term because the team would sacrifice the last few years for the first few years when he's still good.
To get Nash for $7.8 on a 2 year term is not a cap dump, but of course, people here are confused into thinking that he's pure crap, a third liner making all this money.