A few days ago they (The SN/Jays panel) threw up some numbers and graphics that showed he was either number one, or close to it, in terms of defensive metrics for catchers for the league. I haven't actually looked at the fWAR. Throwing runners out if super important, but so are a million other things as catcher.
But, in sum, Jansen's offense has to improve. He's like the auto-out on a slowpitch team that only has 9 players show. Kirk hasn't been much better, but he is starting to barrel up his contact at least. A team strength going into this season is weirdly one of the weaknesses, albeit with a SSS. But if I am triaging, I fix 3B first.