If you think LeSean McCoy's health is the only reason Karlos Williams is seeing the field - think again. According to The Buffalo News, Williams' playing time will continue to increase throughout the season. Unlike McCoy who has struggled to find any running room out of the backfield (he only had 16 yards on 11 carries against the Dolphins in Week 3), Williams has taken advantage of his opportunities. He recorded 110 yards and a touchdown on just 12 carries against the Dolphins.
Although the Bills coaching staff is currently giving McCoy and Williams a 50/50 split when it comes to carries, it looks like Williams will likely begin seeing more carries out of the backfield than McCoy as the season goes on. However, that's not to say McCoy isn't a must-start fantasy player. McCoy is still a PPR machine and will see enough carries to put up respectable fantasy numbers. Williams, however, will sub in for McCoy in all short-yardage and goal-line situations.
Assuming McCoy's hamstring feels good enough for him to take the field against the Giants in Week 4, both Williams and McCoy are startable. Bills head coach Rex Ryan loves to run the ball, so it's safe to assume both backs will see plenty of playing time.