I think Sanderson's best comparable is McAvoy. He's come in and had a relatively good transition, but McAvoy is elite in two way play. He's not as offensively gifted as Makar, Fox, etc... but he's an advanced stats dream and his bridge deal was 3 years $4.9 million before he got his $9.5 million aav deal.
In 2019-20 he was 10th in Norris votes, in 2020-21 he was 5th in Norris votes before getting his $9.5 million deal. His offensive production wasn't as elite in his elc years, and neither is Sandy's so based on other contracts, I don't expect a bridge deal to cost too much. If he changes production, then you don't have to worry about $9+ million in a few years, you pay him, but $10 million for a defensemen is usually going to be reserved for the high end producers. Plus, a 3 year bridge deal gives us so much flexibility to compete with our current core. If we have to move guys out to pay Sanderson, I'd be fine with that since he's already our 3rd most important player at worst and will always be more valuable than Cat, Bath, or whomever by the end of his bridge.