It depends on if you are speaking of a player playing as a PF regardless of his given position, or on a player labeled as PF.
If the player is labeled as PF, JR has no impact on his salary, so the higher the better.
A high JR, could help sell the player as a small forward for inside offense minded team. As SF are so expensive it will probably increase his sell value
Nevertheless, for a player Playing at PF position, wether he is called a guard or a center, JR is not such an important skill.
R&G, Princeton and also Base Offense are the tactics where it's more significant. But in most case Handling is more important.