It remains to be seen what the monstrous offer was, but considering he still has term remaining, held a decent $5.1 million cap hit, and plays a similar style to Carlo, it probably included a top prospect, another first round pick, and maybe another asset.
The Flyers have remained very stringent on Ristolainen despite his value sky-rocketing over the last year and a bit. They still see him as a vital piece of their back-end and should anyone look to pry him out of Philadelphia, they will need to pony up several valuable assets.
It should be noted that this came from Garrioch's latest piece about how the Ottawa Senators should take another run at the Finnish defenseman. If that does come to pass, the Maple Leafs will likely have stiff competition this summer should they rekindle their interest in Ristolainen.