Earlier this morning the Maple Leafs and Samsonov were reportedly working to get a deal done before his arbitration hearing. The two parties were unable to come to an agreement on a new deal and instead the two groups elected to go ahead with the player elected arbitration hearing. As a result the Maple Leafs and Samsonov are no longer allowed to negotiate any further, instead they will be at the mercy of the arbitrator who will now decide Samsonov's contract for next season.
While arbitration is a regular practice, both teams and players can leave a hearing feeling resentment against one another. The process involves each party explaining their point of view, but it is often very difficult for things to not be taken personally. This hearing also ensures that Samsonov will only be able to sign a 1-year deal with the Maple Leafs, as he'll become an unrestricted free agent next summer.