Trouba has been underwhelming so far and I've been critical of him at times but his usage is simply a lot tougher than DeAngelo's...
Tony gets to spend more time with NYR's top forwards but much less time against opponent's top forwards. on top of that, his defensive zone start % is 20% lower and you also account for volume. Not only are Trouba's minutes tangibly tougher, he plays 2:00-2:30 more per game on average, so it compounds. And of course Trouba also has the burden of being the top PK dman which can wear you down and take away energy during the game, esp if a team is getting multiple PPO.
I definitely don't think Trouba has lived up to his contract but I can't see many, if any, defenseman tilting the ice if you were to put them in Trouba's shoes on this team.