As for Garcia you can call him a point forward but he has a .75 to 1 turnover ratio, JR has a 1 to 1, which shows JR is better then Garcia in passing and playmaking.
Not necessarily. Denver gets out on the fast break far more than the Kings do and just run more overall which is more conducive to racking up assists. I haven't seen too much of Garcia, but from what I've seen he is a very smart player which probably makes him a much better decision maker than JR (which in fact he is terrible) which is being very underrated.
On a young team that's looking to improve their players with potential, you want the ball in JR's hands where he can do what he wants. But on a playoff team looking to compete you'd rather have Garcia out there where making the right decisions and being consistent is more crucial. This is nothing to do with who the better passer/playmaker is but who you'd rather put out there on the basis of passing/playmaking.
Just looking at their numbers, rebounding they could both improve immensely. JR being as athletic as he is, he could easily be pulling down 5-6 rebounds a game (obviously given more minutes). However, Garcia is underperforming far more than JR in that category. Because he plays SF and plays closer to the basket, he should be grabbing well over 3.9 boards in 30 minutes.
Shooting wise (3 pt) they're different players with similar stats. JR is the type of guy that could hit 10 straight shots and then miss 10 straights. Much more streaky. Garcia from what I've seen is more consistent make or miss. I'd call it a wash, but given more consistency, JR would be much better.