He played 5 games in this tournament, and he was fantastic in the 4 that he actually had two functioning ankles to skate on. Judging him off the one game where he was clearly laboring is pretty silly. His defense was actually really sound in the other games, including the one against a good team in Sweden.
One bad turnover that probably came out of desperation due to not being able to rely on his biggest strength (skating) is not being “exposed.” It’s just one bad play. And if USA hadn’t totally sh!t the bed and got down multiple goals in the first place Luke probably wouldn’t have been on the ice at all. There were shifts he literally could barely skate.