What if the catcher can not only play defense but can also hit and win games with his bat and speed? I am not advocating that we keep a catcher who cannot catch defensively. So far Swihart has shown the ability to play defense as well. If he falters in that regard then sure, do not include him on the roster. So far he has actually more than held his own defensively once he was given a chance to play regularly-and has won at least one game with a walk off hit.
Data? Vasquez has a dWAR through when he got hurt of -.2. Swihart has a dWAR for the year of -.1. Not much difference. But since Swihart started playing regularly about June 15 his OPS is over .800. Vasquez is under .600. Who do you want on YOUR team? Leon has a dWAR of 0.6 for the year, but his OPS is just over .600. You can argue that Leon should be the other catcher, but IF Swihart keeps playing well he has earned a spot on the postseason roster.