Collins feels like a Brady Clark type, who also debuted at 27. I think Clark's 4.7 career bWAR is a number that Collins could probably hit, but it's hard to see his ceiling going much above that.
The market for decent relief pitching is insane this winter. The Mariners had to pay a top-50 prospect to get Ferrer from the Nationals, and Ferrer's numbers are in the same ballpark as Zerpa (+1 extra year of control for Ferrer).
Just watching how the postseason unfolded this year, an Isaac Collins-type is not going to be a difference maker while reliable bullpen arms were worth their weight in gold. The Brewers absolutely think they can find replacements for Collins and Baddoo is surely one of several options that they will evaluate to fill in the outfield.
If we think our FO is smart than we should be transacting heavily and trying to get little advantages wherever we can.