Just looking up something in 82games, and came across this.
Dion's played less than 1% of the available time at PG, getting decent stats. He's spent 38% at shooting guard, and 13% at small forward, so about 1/4 of the time he's on the court he's spending at small forward.
His opponent's PER is 16.2 at SG, and 13.2 at SF, not much of a change. Shots drop from 22.6 to 17.6 per 48, Rebounds and fouls go up a little, assists goes down a little, nothing you wouldn't expect from switching from SG to SF.
His PER at SG is 15.6. About average for a shooting guard.
His PER at SF is 4.0
He drops 100 points of TS%, combined with his free throws going from 7.0 to 4.7, drops him from about 20.3 points per 36 down to 11.9. Basically, on offense, he goes from being very productive with average efficiency into Alonzo Gee.
If I were Dion, I'd be pissed too.