Indianapolis Colts linebacker Darius Leonard has gone from a relatively unknown player to the NFL's defensive rookie of the year.

Some questioned why the Colts selected Leonard, who played at South Carolina State, a Football Championship Subdivision school, in the second round of the draft.

It didn't take long to realize why the Colts liked Leonard so much. He dropped into coverage and showed off his athleticism by going up to intercept Andrew Luck's first pass during training camp.

Linebacker Darius Leonard and the Colts came up with a turnover in 15 of their 16 games this season. Photo by Leslie Plaza Johnson/Icon Sportswire
That was just a start for Leonard, who won award Saturday night at the NFL Honors event in Atlanta.

He led the NFL in tackles with 163, 19 more than the next closest player, even though he missed a game this season. Leonard also had seven sacks and forced four fumbles. His maturity allowed him to shoulder extra responsibilities put on him by the coaching staff in leading what ended up being a very underrated Colts defense.

Colts general manager Chris Ballard bypassed talented linebacker Roquan Smith to take guard Quenton Nelson with the No. 6 pick because he had his eyes set on Leonard -- who turned a lot of heads during the Senior Bowl in January 2018 -- in the second round.

"One of the things that Chris and his staff do when they are doing all the research on these guys and there are certain players and their draft cards, they are marked in a certain way where we would designate them or identify them as kind of Colts players," Indianapolis coach Frank Reich said. "These are the kind of guys who have the DNA, the makeup of everything that we are looking for -- all the intangibles, all the character qualities, everything about them. It's a really hard filter to get through to get marked that way, and both Quenton and Darius had that on their card.

"So that says something about their maturity and how fast we think they will develop."

Leonard also was named to the All-Pro team this season. He said he was "heartbroken" when he wasn't named to the Pro Bowl.

If his rookie season was any indication, Leonard will be named to plenty of Pro Bowls in his career.