I read Ayn Rand, I don't mind walls of text.
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ADA is supposed to be an all out offensive defenseman who sucks defensively, Trouba is the 8 million dollar all situations shutdown guy. I don't expect Panarin to nail guys into the boards, just like I don't expect Brendan Lemieux to score 40 goals. Different players have different roles, expectations, salaries, etc.
In the past few games ADA has made a couple bad passes that resulted in turnovers, although two were caused by Panarin blindly throwing no-look passes to him at inopportune times (such as when a powerplay just ended and ADA would obviously be backing up). A stark difference is when ADA makes mistakes he's a good enough skater to get back in time, and actually puts effort in and hustles his ass off to backcheck. Trouba not only skates very slowly and forwards have to bail him out on a nightly basis, but it doesn't even look like he's trying as I see him just gliding back.
If you like; tomorrow night you can make note of all the mistakes ADA makes, and I can PVR the game and go back and analyze them and give my take. I can do the same and provide a list of Trouba's mistakes if you like.