Bieber can still be given a qualifying offer, so if he has a good last few months, you can give him that and either bring him back for that price, or get a pick for him. I'm guessing he just hadn't shown quite enough in his time back from injury that the team got any real offers for him.
Springer, given the 10/5 rights, probably only had a couple teams he would have been willing to go do, and so I'm guessing the team just got nothing offered back for him, probably not even salary relief.
The return on Gausman seems light, still. Both guys seem to have top end potential as utility players, not the sort of guys I tend to like to deal for. If Gausman was having a terrible season or something, then sure. But he's been a decent, if a little unlucky, starter this year. At least it feels like you should get back a few more guys like they got in the Hoffman deal, maybe longshots but with higher upside.
The big question still to me is whether it was worth moving one of your top prospects at the deadline for Soriano. Sure, it sets you up better for the next few years, but it feels weird to pay deadline pricing. Could you have waited until the off-season and got a similar deal?