Dude, I’m not sure you understand how metrics work. Him being a number 4 in Arizona means he is playing against the same competition as any other number 4 defenseman in the league. If his metrics are good playing against the same players as Ceci- it means he’s a better player. Your example, Nurse being the Oilers slotted number 1 d man and putting up poor defensive metrics compared to other numbers 1s means he is a worse player.
Or, according to you, Carter Savoie, if offered a contract is December, was wise not to sign it