Jamaal Charles was producing at a RB1 rate in the five games he played last season. The coaches know the talent they have their backfield, and Charles is able to take advantage in both the passing and rushing game.
In addition to his talent, Charles plays in a run-first system (Kansas City finished sixth in the league in rushing yards as a team in 2015). He has a safe hold on the starting job, and he hasn't showed any signs of slowing down.
Even though Charles is the clear starter, the Chiefs did just fine without him last season as Spencer Ware and Charcandrick West took over. Those two haven't gone away, and will likely have a good role in 2016 in an effort to keep Charles fresh and healthy.
Health will be a big issue for Charles moving forward as he's now had two seasons cut short due to devastating injuries. He'll also turn 30 years old in December, and backs start to decline in production at that age.
Charles is used to having his touches limited, so Ware and West shouldn't deter you too much. His age could end up being a factor, but he's still a back that has averaged over 5.0 yards per carry in every single season he's played.
Charles should be viewed as one of the elite backs this season.