The Colts underwent an intentional transformation on defense a year ago, adding veterans up front and injecting youth into the back end of Gus Bradley's group.

Defensive ends Samson Ebukam and Jake Martin and defensive tackle Taven Bryan joined as free agents, while veteran cornerbacks Stephon Gilmore and Brandon Facyson exited, as did safety Rodney McLeod Jr. The Colts rolled with a few returning second-year players (cornerback Dallis Flowers, safeties Rodney Thomas II and Nick Cross) and draft picks (cornerbacks JuJu Brents and Jaylon Jones) to fill those spots.

"We had some veteran players – then I just said look, we're going to go young in some spots," general manager Chris Ballard said. "We went young in the secondary and look, there were some rough moments at times in the secondary and I don't completely put that on them. I put that more on me, but how do you ever develop any continuity, especially with your own guys, if you don't just play them? So I decided to go young."

The results, as usually is the case with a focused youth movement, were mixed. Flowers, Jones and Brents all individually had their moments – like Flowers' breakout game against the Los Angeles Rams that ended with him sustaining a season-ending Achilles injury – but the Colts finished 2023 with the sixth-highest explosive play rate allowed in the NFL (14.7 percent of opponent pass attempts gained at least 15 yards). And despite setting an Indianapolis-era franchise record with 51 sacks (fifth in the NFL), the Colts allowed 24.4 points per game, 28th in the league.

"We took our lumps at times but I think it's going to pay off down the line for them," Ballard said. "I think we had five or six new starters on defense. We did do some good things now. It's not like it's all bad.

"The points do need to come down. We'll continue to have long discussions about where we're going and how we'll get that done. But saying that, we had new starters on defense. We did do some good things too. We got after the passer pretty good. I think it's got to be a little better but 51 sacks is pretty good. Took the ball away, we need to be a little better there in that area and we have to take away the explosives. But I would expect us to take another jump here this year on defense."

Up next for the Colts are decisions on three impending unrestricted free agents who started in 2023: Cornerback Kenny Moore II, safety Julian Blackmon and defensive tackle Grover Stewart. Moore (seven seasons) and Blackmon (four seasons) were easily the most experienced players in the Colts' secondary, while Stewart has proven to be one of the NFL's best, most valuable run-stuffing interior defensive linemen. The Colts also have a few defensive line depth pieces hitting free agency in Tyquan Lewis, Bryan and Martin. 

But surrounding decisions on those players, as well as outside free agents and the NFL Draft, is an ascending defensive core. 2021 draft picks Dayo Odeyingbo and Kwity Paye set career highs in sacks in Year 3, while linebacker Zaire Franklin set the franchise record for tackles in consecutive seasons. Fellow linebacker EJ Speed totaled over 100 tackles and made several splash plays against the run and pass in his first year as a full-time starter, too. Defensive tackle DeForest Buckner, of course, continues to be a force in the interior of the Colts' front – he had the seventh-highest pass rush win rate (15.3 percent) among defensive tackles despite a high rate of double teams from opposing offenses. 

And then add in those young defensive backs, who intentionally saw playing time in 2023, and the Colts believe they have a solid core in place for Bradley to work with again in 2024, his third year as the team's defensive coordinator. 

"This year we were able to set a franchise record in sacks and little things like that," Buckner said. "Obviously, we have some young guys all over the place on the defense, but obviously there are always places to grow – up front and in the back end."