Matthews and Marner are obviously going to be even tougher negotiations than Nylander since they have more leverage due to being better to this point. There's also extra incentive to not let either negotiation go into the season this time around.
Ideally, I would have preferred Nylander's AAV to be slightly less. However, what was the alternative? Not signing him at all likely would have resulted in an eventual trade IMO because of the aforementioned - and other - RFA's that soon have to be re-signed. Otherwise, it's tough to know how close any trade was, if it all, not to mention the team and return involved if there was a possibility of it happening.