You don't offer him or Tavares a contract until after the playoffs. Would be dumb to extend him now, he knows his time as a Leaf is on the line if he doesn't perform. He's been playing with a fire lit under his ass all year, last thing you wanna do is give him that security that he gets to stay on his favorite childhood team for another 4-5+ years.
Let's see how he performs in the playoffs and then decide. If we absolutely had to sign him now, offer him the same amount that he's currently making. He wants a raise? Show us you can get it done in the post-season.