Severson is behind Mueller, Lovejoy, Greene, and Butcher if you solely look at the ratio.
But if you look at net takeaways and giveaways divided by minutes played, which seems more logical to me, when you do that you get in order from best to worst:
1) Mueller
2) Lovejoy
3) Greene
4) Santini
5) Vatanen
6) Butcher
7) Severson
8) Moore
Severson actually coughs up the puck more per minute than any other Devils defesenman. The reason he's not in last place is because he steals the puck more than Moore does, and Moore also coughs up the puck a lot.