Quoting: aedoran
I think the best time to maximize their return was from the TDL rumors until the beginning of free agency. If he has a good season then his value at the upcoming TDL his value will be back up but he won't bring in the equivalent of 3 or 4 1st rd picks until the TDL.
If the Senators are offering two 1sts and a B prospect, Arizona is not going to get that from anybody else. Those two Ottawa 1sts are potentially great assets, because even with Giroux and Debrincat, Ottawa is still a bubble team. If the protection is only top 5 protection, those picks might be in the top half of the round. The Atlantic division is competitive. Ottawa made some huge additions this off season, but that's a bit of confirmation bias, because the reason they were in a position to make huge additions was because they had so much cap/salary space from having a bare team with many needs. Could Ottawa make the playoffs next year? Sure. But it's just as likely that they miss out. There is a lot of uncertainty over how it will all come together.
Someone could argue that they can get a 1st and two C level pieces for Chychrun as a rental, which is true - but the 1st is going to be a guaranteed late pick. There is a whole lot of value in the CHANCE that the Senators (or any bubble team for that matter) Duchene themselves with the picks.
It has been a buyer's market all summer. DeAngelo went for very little. All the big name forwards dealt went for very little (relative to historical trades). Arizona has lucked into Ottawa being a perfect target due to Ottawa's unique circumstances as a budget team who needs to win now but doesn't have the money to acquire a top defenseman elsewhere. By all means, they should push for a strong return, because they have leverage, but if they push too hard and Ottawa drops out, they enter a buyer's market where no one is coming close to matching what Ottawa must be offering for two 1sts and a top prospect to still be a reasonable part of the discussion.