Quoting: mokumboi
Yeah, except Matthews is six years younger, not currently signed to be paid 9.5M until he's 35, scores goals at twice the rate of Stone and centers are worth more than wingers. The difference is NOT marginal.
Contract: Matthews is going to be paid millions more than that when he hits free agency in a few years, no doubt for max term. The Stone contract is a steal, definitely worth the price tag and he's only been getting better, low chance he doesn't provide a net positive value on the rest of this deal. Matthews is signed to the richest RFA contract since McDavid, a big cap hit to swallow. In my opinion, the contract situation is better with Stone. Plus, with both teams built to contend right now, I don't think they care about what's going on 4+ years down the road.
Goal Scoring: Yes, Matthews is establishing himself as the best goal scorer of his generation. Stone is doing the same in regards to his two-way play, being in the upper-echelon of scoring leaders while contributing truly elite defense as a forward. I'd still say Matthews is the better player, but that's why there would need to be a pick or prospect attached with Stone to make it fair value. When it comes to the top 20 or so players in the league, though, the difference becomes marginal (discounting the difference between McDavid and the second-best player in the league).
Position: As I said, Stone takes the responsibilities of a center once the puck drops, as long as he's centered by a capable faceoff guy it's all good. I know positions are important, but not over most other factors.