Kenneth Walker III - Week 6
You may consider it 'jumping the gun' to include Walker-- a guy who is just going into his second season-- on this list, but in his rookie season, Walker proved to be the perfect replacement for the great but oft-injured Chris Carson.
In his first year in the league, the Michigan State product put together an exceptional campaign, finding the end zone nine times and rushing for 1,050 yards on 228 attempts, which is good for 4.6 Y/A.
While it may be only one season to go off of, after watching some of his film and highlights I fully believe Walker will very quickly rise into the upper echelon of running back talent in the league, up there with guys like Henry, Chubb, Barkley, Jacobs, etc.
Now, Walker did just suffer a groin injury during training camp recently and has remained out of practice, however, Pete Caroll himself said that the young HB didn't suffer a "terrible injury" and they are more so just showing precaution so it doesn't linger until the regular season. Barring any other injuries, he should still be ready to go against Cincy by the time Week 6 rolls around.
I will also give an honorable mention to Dameon Pierce of the Houston Texans, another rookie running back who made a name for himself last year. If he continues to develop he could also give the Bengals trouble when he comes to town.