It is not in Andrew Luck’s nature to publicly rebut skeptics who claim he will never become the same caliber quarterback as he was pre-shoulder surgery. That doesn't mean the Colts signal-caller is oblivious to the criticism.

In fact, Indianapolis general manager Chris Ballard believes Luck is using such doubts as motivation as he continues to recover from the damage that cost him the entire 2017 NFL season.

"I think he's got a little bit of a chip on his shoulder to prove some people and naysayers wrong," Ballard told co-host Bill Polian and me earlier this week on SiriusXM NFL Radio. "That's a beautiful thing with a quarterback that I think is top five in this league."

The Colts have taken multiple steps this offseason to help Luck reach those heights upon his imminent return. The first is an infusion of both depth and talent for their offensive line, which has experienced struggles in pass protection for years.

Two of the Colts’ first three picks in last week’s draft — Notre Dame’s Quenton Nelson (first round) and Auburn's Braden Smith (second) — were guards. They will be inserted on the left and right side of the line, respectively, between left tackle Anthony Castanzo, center Ryan Kelly and the winner of the Denzelle Good/Joe Haeg battle at right tackle.

NFL DRAFT GRADES:

How Colts fared with 2018 picks

Because of the position's nature compared to others that can make more of a splash, some NFL coaches and general managers believe guards shouldn't be selected in the top 10 like Nelson was at No. 6. Asked to respond, Ballard laughed and said, "That means they must have them."

Ballard, who described Nelson as "the easiest pick" he has ever made, continued: "To me, a difference-maker comes at any position on the field. We feel Quenton is a difference-maker in both the run game and pass protection. With Andrew, we think he gives him a shot to ascend and be the playmaker he can be with protection. I think that goes hand in hand.

"You can look at the league now and the value people are putting on the interior of the offensive line. They’re getting contracts upward of $12 million, $13 million, which was unheard of three-to-four years ago. They're getting paid tackle money. And there’s such a scarcity up front. I think you saw in the draft when two centers went in the first round and (other) guards came flying off the board early in the second. Offensive linemen are hard to find. You better grab them when you have a chance."

Despite entering the free-agent signing period with roughly $73 million in salary-cap space, Indianapolis didn't spend heavy on offensive skill-position players. The most costly additions were tight end Eric Ebron (two years, $15 million) and wide receiver Ryan Grant (one year, $5 million).

Ballard, though, believes the Colts already had talent on the roster and that new coach Frank Reich’s offensive system will lift players across the board. Indianapolis will be using a combination of a hurry-up offense with concepts Reich learned while serving as offensive coordinator for the Super Bowl-champion Eagles.

"Everyone thinks you have to have dominant wideouts," Ballard said. "It’s great if you do, but you can have dominant (running) backs and two tight ends that play and create some mismatches and problems for the defense. I think you'll see Frank and Nick (Sirianni, the Colts' new offensive coordinator) do a lot of that this year."

As for the running backs, Ballard revealed that Marlon Mack underwent offseason shoulder surgery himself after playing throughout his 2017 rookie campaign with a torn labrum. Mack is still considered the frontrunner to start in a competition that will include Christine Michael (who Ballard said “has looked outstanding" coming off ACL surgery), Robert Turbin, Josh Ferguson, and two mid-round draft picks in N.C. State’s Nyheim Hines and Mississippi’s Jordan Wilkins.

A committee approach is designed to help replace Frank Gore, the team’s leading rusher the past three seasons. Gore, who turns 35 on May 14, left via free agency for Miami.

"It's going to be a competition," Ballard said of the Colts’ running back spot. "They all kind of offer you a little bit of a different flavor."

But if the Colts are truly going to start tasting success again following a 4-12 record in Ballard's first year on the job, Luck must start feasting on opposing defenses once again the way he did during his first three NFL seasons. Luck’s shoulder was originally damaged in 2015, which was the same season he missed the final nine games with a kidney injury.

Luck returned to start 15 times the following year but needed postseason shoulder surgery for damage far more extensive than initially revealed. Luck wasn't ready for the start of the 2017 regular-season as avowed by Colts owner Jim Irsay and then-head coach Chuck Pagano. Luck ultimately was placed on injured reserve when he continued to experience pain while trying to throw.

Ballard said Luck still isn't passing in Indianapolis' voluntary workout sessions and that they still "have a ways to go." However, Ballard did say Luck "is out there giving handoffs and going through the offense. And he’s doing his strength training and all the stuff he needs to do with his (throwing) motion to make sure it's right."

"He’s in as good a place as I’ve seen him both mentally and physically right now," Ballard continued. "But we don’t want to skip a step (in rehabilitation). He doesn't want to skip a step. You don't want to have any kind of setbacks.

“If everything goes as planned, we'll be ready to roll come training camp."

MARVEZ: Ex-Colts GM Ryan Grigson opens up about 2017 firing

Should that happen, Ballard will no longer have to field the constant stream of inquiries that come his way about Luck’s physical status.

"It's funny because they've asked me the Andrew question every way you can answer it trying to get a different answer," Ballard said. "I'm a broken record when I say I believe in Andrew Luck. I believe in the kid. I believe in his mental toughness. I believe in his passion for football. And I believe in his talent."

The next step for Luck is quieting those who don't.

Alex Marvez can be heard from 2-6 p.m. ET Thursday, 3-7 p.m. ET Friday and 2-6 p.m. ET Saturday and Sunday on SiriusXM NFL Radio.