Thanks for the help with mine.
Follow the law of averages. Witten is averaging 6.5 points per game in standard scoring while Best is averaging 14.6. There's really no comparison. Even in PPR, Best has better odds of scoring, and will catch passes. Witten will probably put up his usual stat line: 5 catches for 50-60 yards. In a PPR that's good enough for about 10 points, or 16 if you're lucky and he scores. Best meanwhile, should get his usual workload of 15-20 carries, 50-80 yards, plus has a chance at getting the same number of catches as Witten (and is averaging 5 catches per game after 5 weeks!). Start Best.