INDIANAPOLIS -- The bumps along the way, the ugliness at times and the losses have been there for the Colts this season.

How else can you explain them needing overtime to beat the winless San Francisco 49ers after leading by 14 points in the fourth quarter on Sunday?

The Colts are fine with taking their current lumps -- and any others that will come along in the coming weeks -- because everything is about the big picture for them. It’s a picture that has promise, because general manager Chris Ballard is assembling a young foundation of players who already have started to show they're the type that will fit with quarterback Andrew Luck in the future.

Colts rookie Marlon Mack celebrates after his 22-yard, second-half touchdown in Sunday's win over the 49ers. AP Photo/AJ Mast

Running back Marlon Mack became the latest rookie to get in the mix when his big-play ability likely saved the Colts against the 49ers. The fourth-round pick out of the University of South Florida rushed nine times for 91 yards and a touchdown against San Francisco.

“Marlon is a guy that comes in to work,” Indianapolis receiver T.Y. Hilton said. “He was dealing with injuries early on. He’s starting to get healthy. He adds another dimension to our running game. Having that explosiveness back there means a lot.”

The Colts were looking to add another dimension in a backfield that already featured veterans Frank Gore and Robert Turbin, who are both considered power backs rather than speedy backs. Mack complements those two because he’s more inclined to get to the edge and turn on his speed.

That was the case against the 49ers, as Mack averaged 14.2 yards per carry in the second half and in overtime, according to ESPN Stats & Information data. He had 35-, 22- and 16-yard runs during that span. The 22-yarder was a touchdown, and the 16-yarder was a yard short of being another score for Mack, who missed time earlier in the season with a shoulder injury.

“It feels good to come back from an injury and go out there and show people what I can do,” Mack said. “Go out there and show them why they drafted me for and to perform like they know I can.”

What you need to know in the NFL

• Statistics

• Scoreboard

• 2017 schedule, results

• Standings

Ballard, wants to build the Colts roster through the draft, like what happened when he worked in Kansas City prior to his arrival in Indianapolis, rather than try to take shortcuts with aging veteran players in free agency.

At 34, Gore is in the final year of his contract, and Mack has the potential to be his replacement if he can continue to develop and remain healthy. If so, the Colts are in position to have their strongest draft class since the 2012 group that was highlighted by Andrew Luck and Hilton.

The Colts' first-round pick, safety Malik Hooker, already has three interceptions this season. Their second-round pick, cornerback Quincy Wilson, is a future every-down starter for the Colts. And fifth-round pick Nate Hairston has been the team’s slot cornerback in every game that he has played in.

It has been a struggle for the Colts this season, but the vision Ballard and the rest of his front office have for the future is slowly starting to come together on the field.