At the end of the day this is sports. Anybody trying to reduce it to what a spreadsheet says is doing it wrong.
Carolina has played well in the last two games. They have every reason to believe they deserve the split out of games two and three. They had carried the play for long stretches during both of those games.
What it has come down to is that the Rangers have an ability to generate a high quality shot off of a high danger chance, and Carolina doesn't take any high quality shots. They lack the finishing ability. The HDCs they get either miss the net (aka hit posts) or Igor is making the save. They just don't have any natural finishers the way the Rangers do.
I said this many times about this team, they take what you give them. Carolina isn't giving them much, but when they give, the Rangers take and it winds up a goal.