While Gionta scored 29 goals in his 2nd season with us you could clearly see the decline. He was given lot of TOI that year and his performance was not bad but certainly not great. He was playing close to 20 minutes a game and did 46 points in 82 games which is kind of not very good for this TOI.
Toffoli will do well for us over his contract and this is a good contract. But expecting another Ovechkin like season next year is setting the expectation too high.
Every player is different, in terms of when they decline. We will see who Toffoli is over the next 3 years.
It's encouraging that not only are his numbers up this year, but also last year in Vancouver. I.e. his numbers are up ever since he left LA. I.e. what we've seen the last two years may be more the real Toffoli than we saw in the LA system. But we'll just have to wait and see. It's too small of a sample size for me to make trustworthy projections.
I also like that he should have good players to play with (Suzuki, Caufield, Gallagher, Anderson, and KK). And, I hope we either keep Danault and Tatar, or replace them with players that are as good or better offensively - i.e. not Lehkonen and Byrons.