If Kakko scores that open goal in game 1 and put home the chance he had early in game 3 (both in this series against Carolina), we are not talking about his play. I think he might be gripping the stick a little tight right now and not finishing his chances, but he is doing his job defensively. I do wish he had a higher gear because his acceleration is terrible. His overall speed is fine, it just takes too long to get there. However, his game is made for the playoffs. The top lines always want to score off of the rush. The kid line does the hard work and cycles, which is why they are often dangerous and the other lines can look useless at times. This is also the reason why Kakko can look lost with the other lines. His game is not a good fit for the run and gun guys. This is probably why the Panarin supposedly doesn't like playing with him. Their games are very different.
I think this is also why Laf has had a hard time at points with this team. His game better matches with Chytil and Kakko than it does with the guys who just want to blaze up the ice. You are seeing 3 guys who work the boards and cycle. Kreider and Copp are the only guys that consistently do that on the top lines. I really wonder how well that line would work with Copp as the C vs Chytil. Chytil's shooting percentage (5.9%) is his lowest in his 3 seasons as a regular player. That is terrible news for the moment, but hopeful news for the future considering he should go back to roughly 10% or 11%. He is already better in these playoffs at around 8.7%.
A temporary time on the 4th line is no big deal. He took it like a champ and played hard. He really does need to get a skating coach to work on acceleration. His agility and edge work are great, but he needs to get up to speed faster.