Quoting: TheresAlwaysNextYear
It is an overpay. Kucherov, who put up 128 points, signed for 9.5 for 8 years. Marner isn't worth 500k less and 5 years less
Kucherov is a bad comparison. He signed his deal in 2018 after putting up 85 pts and 100 pts, so in that you're right he's a good comp, however where the comp fails is that Kuch plays in Tampa, where there is no state tax. If you'll notice, both Stamkos and Kuch, two players better than Marner both signed for under 10m, because they don't have to pay taxes. This is also the reason why Point will likely sign for less than 10m as well. TPA doesn't have to pay guys 10-12m per, because 8m goes just as far in FL.
Kuch and Stamkos also both publicly stated they signed their deals for LESS MONEY because they knew TPA would be facing a CAP crunch and they wanted the team to be able to stay competitive and they both wanted multiple chances to win cups with the Lightning
Now, you can certainly argue that maybe Marner should take a play out of their books and sign for less money to allow TOR to remain competitive and try for multiple cups with their core. But you certainly can not argue that he should be paid less than 9m because Kuch only makes 9.5m... by that ridiculous logic, no player should ever sign for more than Kuch. Panarin shouldn't have gotten 11+ from NYR, JT shouldn't have gotten 11 from TOR, Matthews shouldn't have gotten 11.6 from them either because none of them are better than Kuch.