Its the configuration. You can't have 4 of the top 15 highest paid players on one single team, especially when they are all forwards. Goals in the playoffs are difficult to get, especially at the rules loosen a bit. You need plenty of traffic and players in the paint, it isn't rocket science.
They need to spread out the cap so that they can have balance and depth running 4 lines.
The Leafs were built better than the Oilers for years and I like Leafs D better. However, Oilers were wise to get Hyman who always played the right way but has really exceeded all expectations. Then they pick up guys liek Kane and Perry, players the Leafs would NEVER take a flyer on because they were out of favor.
Leafs like their nice players. The type that bake an apple pie with Mom and sell jerseys. Kane and Perry were added to the Oilers for nothing, no traded needed. It is a culture decision.