Joe -- like a lot of serious martial artists -- realized the limitations of a strictly p/k curriculum. I recall reading a year or two ago that he was pursuing grappling and MMA, and thought "well, I might have known."
It doesn't surprise me that he is "decent" at it. He is gifted athletically and spatially, and also is very focused and disciplined. I always liked watching him train at the dojang, and even got some good tips from him that I have kept with me over many years.