Colts' draft class featured a speedy running back and ball-hawking safety

Fourth-round pick Marlon Mack had 583 yards from scrimmage and four touchdowns this season. Andy Lyons/Getty Images

Indianapolis Colts general manager Chris Ballard's first draft class was full of players who made a solid impression by showing that they can be key contributors in the present and the future.

Grade: Average

Best rookie: Running back Marlon Mack showed enough flash throughout the season to be at least a rotational player, with the possibility of starting next season. Mack, who became Frank Gore's backup once Robert Turbin (elbow) was lost for the season, rushed for 358 yards. Mack had six rushes of at least 20 yards and four receptions of at least 20 yards this season. ... First-round pick Malik Hooker would have won this honor had he not torn his ACL in Week 7 against Jacksonville. He had three interceptions in just seven games.

Most improved rookie: Cornerback Nate Hairston went from being just another cornerback added to the roster, after he was selected in the fifth round, to earning the slot cornerback spot. Having Hairston allowed veteran Darius Butler to make the full-time switch to safety. Hairston had a balanced season, finishing with 35 tackles, 2.0 sacks and an interception.

Most disappointing rookie: The opportunity for snaps at inside linebacker was there for Anthony Walker. The problem was that the fifth-round pick out of Northwestern struggled to stay healthy. Walker was inactive due to injuries six times during the season, and he dealt with injuries in training camp. Walker, who got the majority of his snaps on special teams, finished his rookie season with 22 tackles.

Jury is still out on: One of the biggest mysteries most of the season was the lack of playing time for second-round pick Quincy Wilson. The cornerback out of Florida had a strong Week 2 performance before he suffered a knee injury. Then he was criticized for his practice habits before becoming a healthy inactive. Wilson, who fits the tall cornerback mold that Ballard likes, was inactive for eight games -- including as a healthy inactive for four of those games -- and didn't see snaps in another before injuries put him back into the lineup for the final five games. Wilson closed his rookie season with an interception on the final play of the game in Week 17.

Undrafted rookie evaluation: Punter Rigoberto Sanchez beat veteran Jeff Locke for the job in training camp and then helped ease the loss of Pat McAfee, who abruptly retired last winter. Sanchez averaged 44.8 yards per punt while landing 28 punts inside the opponents' 20-yard line. ... Center Deyshawn Bond started the first four games of the season before he tore his quadriceps against Seattle.