Exactly. It's amazing that more people don't recognize this. If Sbisa gets top4 ice, is he a top4 Dman? TOI is just one marker to determine the quality of a player. There are others like quality of competition, QoT, GA20, CorsiRel etc...
How are you determining this?
And he became this way because he became more efficient at what he does, or he was just given top4 ice? Please read CanaFan's comment above.
There's nothing vague about it: They needed a top4 Right-Side D (not necessarily a Right shot D) and Gudbranson has not performed like a top4 right side D. This would be an easier discussion if you placed anything in possession metrics.
What changed? We're not talking about trading Luongo's contract (what it was made out to be by the league) for an ELC D prospect.
The point about DET is that they pay their premium contracts to players that generate points first and foremost. Kronwall and Green. Benning is just about to make Gudbranson the highest paid Dman here, hence, the contrast.