On the Sharks Burish is:
Not a top 4 PKer talent-wise
Not a top 10 5on5 forward
Not a top 6 PP guy
Not an energy guy
Not a physical guy
Not a fighter
With that, it's hard to justify anything more than a $600k/yr 4th line plug. And generally that 4th line plug you'd prefer to be a younger guy who has a chance of getting better, or use it for rotating AHL callup as a reward for the AHL guys you value.
Basically, if Burish doesn't have that contract, he's likely not on the team. DW is great at signing/trading top 6 forwards and top 4 d-men. It's those contracts to 3rd/4th liners and 3rd pairing d-men that usually don't work out so well.
Edit: This is based on last year. I really hope he develops into the best PKer on the team and brings something to each and every game, even if it doesn't show up on the stat sheet. Last year, you could have replaced him with any AHL plug and I don't think the Sharks fare any different.