How do you know you have a good catch dog?

I am with y'all on that. Years ago I had a Pit that was straight ear. One day we saw 3 boars crossing a burned area in the marsh and I turned Billy loose on them. It was a foot race and he was pulling up alongside of the boar to grab a ear when they hit the thicket. If he would have grabbed the HQ and spun the hog he would have caught it but trying to get to the ear the boar made it. We still caught him but it was 2 hours later after we put a couple of Plotts on him.
Another instance turned Billy loose on a big boar that had no ears and he really had a hard time holding him. Got shook off a couple of times before he finally got hold of the side of the head. In a perfect world I wish I had a bulldog that could adapt a little faster to certain situations.
Other then those two instances Billy was as good as they got for a catchdog.