Great chin. One of the best among the lineal HW champs. Stopped by only two men, both big punchers. In the Louis fight, he went down after taking dozens of power punchers from perhaps the best offensive fighter of all time. Against Nova, he was stopped on a cut and on his feet after taking a lot of punishment in both fights, and these fights were near the end of his career as well. Survived other big punchers like Schmeling, Galento and Uzcudun among others. Got hit a lot throughout his career and aside from the Louis and Nova fights, was never really in danger of being knocked out. Like I said, his chin was about as good as it got at heavyweight.
You should have added a poll with a value scale on it. Baer's chin was not bad, but not incredible either. On a scale of 1 to 10, I'd say a 7.