Yeah if I had to rank those 4 I would put Weegar and Brodin at the top, Weegar has the offensive advantage though so definitely edge to him (top like 20-35 defensemen). Then Pesce like 15-20 spots back and then Trouba somewhere as you said in the top 50-60 range of defensemen. In terms of skill Trouba isn't even the 2nd best defenseman on his own team, I would rank all 3 of Fox, Miller, and Lindgren above him. Trouba is captain material, he's a good team leader which I think is very important but if we are just talking skill he is a #4 on a good d-core like Tanev, Carlo, or Cernak, the aforementioned Pesce, Brodie, etc. A guy who's primary role is killing penalties and shutting down the opposition. You can expect some offense from him but not a lot.
If Weegar returns to being a 50 point defenseman (like he was pacing at the end of the year) while also staying elite defensively then there is not a single person who would ever take Trouba over him