Fantasy Upside
Mack showed exciting breakaway ability in his rookie season on limited touches. Of his 93 carries, seven went for 15+ yards. He is also cleared for the start of training camp after recovering from a shoulder injury this offseason. The Colts adding mauling Notre Dame guard Quenton Nelson doesn't hurt either. Frank Gore's departure opens up 290 carries, creating a massive opportunity for Mack to emerge.
Fantasy Downside
The Colts' new coaching staff has indicated this will be a full running back by committee (RBBC), but with Gore gone and Robert Turbin now suspended four games, the question will be whether it's a two- or three-man RBBC. Mack did have breakaway runs last year, but he also had 30 of his 93 carries go for zero or negative yardage. Coaches hate that kind of dancing behind the line of scrimmage. His pass protection is also in question.
2018 Bottom Line
Mack is a legitimate sleeper but will have to fight off rookies Nyheim Hines and Jordan Wilkins for volume. He's being drafted outside the top 24 of running backs in the middle rounds and is a gamble potentially worth taking in an Andrew Luck offense with an upgraded run blocking offensive line. His 10.7 yards per reception production from last season also makes him attractive in PPR formats at his price.