First, on what the Blueshirts gave up to the Blue Jackets:
*Neither Dubi nor Arty have reached their potential and there is no telling if either ever would have in New York. Dubi could have been an Arnott-esque force but he struggled to reach that level with any kind of consistency. He got the big contract and, as is typical, struggled in the first season of the deal. In postseason interviews he acknowledged it and promised to work to be better and now, Columbus will find out if he stands by his word. Arty had multiple 'wow' moments but they came when he was paired with big, tough wingers. Without burly Blueshirts to have his back, the Russian played on the fringes and was ineffective.
*Losing Tim Erixon is the most painful part of this deal. To let Erixon go and keep Del Zaster is simply stupefying. In 18 games last season we saw Erixon improve and adapt, held back only by his size and the ice time allotted him. Meanwhile Del Zaster continues to make the same mistakes now that he did three seasons ago but Torts loves him so he avoids any accountability for his errors. That being said (through gritted teeth), Erixon is now unlikely to become the great player he could have been, as he will surely be unhappy in Ohio - a worse locale than Calgary, where he refused to play in the first place.
*The first rounder will likely be late teens, early 20s so it really isn't that big of a loss. When you consider that the kids that are in the system now, outside of Kreider, will need a few seasons of seasoning before coming to Broadway, losing one pick isn't the end of the world.
And now for Nash:

*Those instincts may be completely wasted in Tortorella's uncreative, talent-stifling, killer instinct-lacking, shot-blocking, defensive system.
*There is no denying the multiple moments of singlehanded sheer brilliance Nash has performed but, in typical fashion, the Rangers picked up a player who's numbers have decreased each of the previous three seasons.
*He is signed for the next six seasons, at an exorbitant cap hit of $7.8 million. Given that the NHL is looking to lower the cap, having a massive hit like that for what, come January and a full recovery by Gaborik, will be the second-line right winger is more than a little silly. He has a higher cap hit than Stamkos, Parise, Kovalchuk and Vanek (among many others).
*The captain of Columbus, Nash asked to be traded - a request that was made public and a sure reason to worry about his character. That being said, he stepped up his game with nine of his 30 goals in the 20 games after the trade deadline - either to make other teams more willing to increase their offers in the offseason or because there was no more pressure to carry the BJs.
*The only real centers during Rick's time in Columbus were old Sergei Fedorov and unhappy Jeff Carter, but he played alongside Joe Thornton in Davos during the last lockout (and may again in the next one!). Automatically thinking he will star alongside Richard$ may be a mistake; adding Gomez to Jagr seemed like it would be a sure thing but we all know how that worked out. Perhaps Nash can fall in with Derek Stepan, and help the kid meet his potential.
*As an outsider, it did not seem like Nash helped anyone in Columbus meet their potential. Gilbert Brule, Derick Brassard and Nikita Filatov all busted under his watch (there is still a little hope for Brassard, but who knows).
*It is interesting that Hockey-Reference lists former Ranger Bun Cook as a 'player with a career of similar quality and shape.' However, the Blueshirts are hoping and paying for Nash to be more Bill Cook than Bun though, as Bill was the best winger in the game and he led the team to two Stanley Cups.
And that is what it will come down to: winning Stanley Cups. The team just choked away a prime chance and the flash of adding Nash will be long faded if the team doesn't take the next step next season.