Looks somewhat hilarious at first glance.
I could see there being reason to the madness though. Haggsta is a reasonable PK’er whereas Petterson is our least used D-man on that unit with Matheson, and neither are used there unless we absolutely have to. He’d also be our most prominent hitter, and would play sheltered ES minutes.
If Petterson goes the other way, it gives us added cap-flex to address F and also gives meaningful relief for the Summer, where we’d have an in-house option in POJ or Friedman.
Of course, Petterson should be worth a good deal more than Hagg, but the other issues mentioned might make this a low-key win/win for both teams.