Nuggets forward Michael Porter Jr. recently agreed to a five-year, max rookie contract extension, shoring up his position as one of Denver’s top players and a key franchise piece. Hobby wise, Porter Jr. cards have seen some nice gains over the past year or so, but let’s examine how three of his most popular RCs are performing in the current market: 1. 2018-19 Panini Prizm #32 Michael Porter Jr. RC ($15-$40) Raw prices for 2018-19 Prizm RCs have been softening for some time now, and Porter Jr. is no different, down two price levels from a previous $25-$60. Any further…