Rossi doesn't drive anything offensively yet either btw. I'll say he isn't really a true line driver yet, because "doesn't drive anything offensively" makes it sound like he's purely a passenger, and he isn't. He just isn't the main driver on the line.
You're also comparing Ek's 26 year old season to Rossi's 23 year old season and I hate sounding like a broken record but people keep comparing Rossi at 23 to other guys at 26 or later to prove that those players are as good as Rossi, but compare them at 23 and Rossi is miles ahead, so what does Rossi look like at 26, 27, 28?
Ek is a good hockey player, so he's going to do things good hockey players do, but he is limited offensively, like Rossi is limited defensively at this point. If I have to choose one to play in an offensive role and one to play in a defensive role, I can make that decision easily without second thoughts.