Mack is trying to gain a little bit of weight to prepare for the possibility of an increased role in his second NFL season, Andrew Walker of the Colts' official website reports.
A fourth-round pick, Mack was feast or famine in his backup role as a rookie, averaging only 3.8 yards per carry despite taking six of his 93 totes for 20 yards or more. For context, fellow rookie Aaron Jones was the only player with a higher percentage of carries going for 20-plus yards (min. 50 attempts) and he averaged 5.5 per carry. Mack displayed a similar mixture of potential and inconsistency when the Colts threw the ball, impressively averaging 10.7 yards on 21 receptions but struggling with his pass blocking and catch rate (63.6 percent). He's left atop the depth chart after Frank Gore signed with the Dolphins, though the Colts likely will add competition during the upcoming draft. Mack's pass blocking will be of particular importance, as the Colts don't want Andrew Luck (shoulder) to take the kind of beating Jacoby Brissett was subjected to last year. Their current group of running backs may be the league's worst, with Mack joined by Robert Turbin, Christine Michael, Josh Ferguson, Matt Jones and George Winn.