The biggest benefit of this trade would be to just get Pettersson off the books. If it’s a mid-level prospect or a mid-round draft pick, it’s likely not going to matter a whole hell of a lot to the Penguins. Considering the Red Wings currently sit with 16 draft picks in the first four rounds of the next two NHL Drafts, they have some picks to pluck from.
$4M cap hit for four years on a 2nd-pairing 25 year old isn’t terrible to be honest but this seems a bit like getting the new Danny DeKeyser in before getting rid of the old one.