De Haan's contract is realistic for going through FA and I feel that it is good value, however, why would you sign him and force Sergachev to be 7th D? He spent time on the 2nd powerplay for most of the year and even some time on the first. Signing De Haan doesn't make sense.
Also, Tanev, while coveted by many, is an injury liability and is not as elite as many people think. If you really want him you could give up Johnson straight up. You wouldn't have to include Koekkoek and a 3rd.
While I agree with getting rid of Coburn, I disagree with the Girardi move. He was brought in to be a defensive, shutdown guy and he has done that and then some. He's great at blocking shots and provides depth in bottom pairing. Stralman is paired with Hedman so that leaves Dotchin (I agree he will be on next year's roster) and Girardi to pair with McDonaugh.
You claim to be "Fixing the Defense" but it doesn't look broken to me.

I choose De Haan because I feel like a rotation of De Haan and Tanev is better than Coburn and Girardi... Serg also played on the right side last year, so really I feel like Dotch is the 7th. The bigger reason I moved both Coburn and Girardi is the amount of cap space left to resign Gourde, Kuch, Point and Vasy. That's what I was trying to create here was the cap space to resign the import pieces for next season

why not send Coburn to the AHL his cap will only be about $2,500,000