TO needs a better 3rd and 4th lines, just being able to play defense, only, isn't what productive lines do to help win in the playoffs.
Players like Jarkrok, Kampf, Reaves, Lafferty, Holmberg and Gambrell are all the same types of players in that there's a definite lack of talent and TO has needed more offensively capable players in the bottom two lines for when the top 2 lines run dry as they have in the last 6 years in the playoffs.
On top of these anemic bottom 6 forwards TO has had and indications are that it will continue, TO has had a significant talent void on the defense, the d has been reasonable defensively but outside of Rielly there hasn't been any true support for the offense from the d, this has been successful during the regular season but it a true and constant problem TO hasn't addressed in the Matthews era.
I thought trading for Gustafsson was an attempt to address some of TO's issues with playoffs offense but he was benched and TO had predictable results.
TO might not be as sound defensively this year but it might be more balanced which could give us greater hope for success.