Quoting: palhal
Jarnkrok....6th in Leafs points among forwards, 6th in Leafs goal scoring among forwards. 5th in plus minus among forwards. Don't know how his numbers make him a low 3rd or high 4th liner guy, except for maybe his salary.
Rankings are against other forwards with 500+ min, 5v5.
He was 187th in expected goals (8th on Tor)
178th in Corsi % (7th on Tor)
196th in on-ice expected goal against per 60 (7th on Tor)
273rd in on-ice expected high-danger shots against per 60 (11th on Tor)
178th in created xgoals (7th on Tor)
He mostly played with Tavares, Matthews, Marner, Engvall, and Kampf
With the top line guys he was good but guys like Bunting and Kerfoot were better. With Engvall and Kampf, Jarnkrok was bad.
Now, it is possible he is just better with more responsibility but it is more likely he is a product of great linemates than causing their betterment (by a statistical margin).
Edit: He doesn't play in the dirty areas, which can be seen as vanilla.