Everybody has heard by now about the unprecedented choice Nick Saban made with his team struggling to a 13-0 halftime deficit during the College Football Playoff National Championship game. But few people know it wasn’t the first time Saban had a tough decision to make about replacing a veteran, winning quarterback with an untested but clearly more talented passer.

Saban’s on-the-money decision to insert freshman Tua Tagovailoa into the game against Georgia was almost certainly the impetus that earned Alabama its fifth national championship in nine years.

But in 2009, as the Tide was on the way to their first national title under Saban, the stakes were equally high. After much internal debate, Saban chose to stick with his veteran and was rewarded with the only perfect season of his career so far.

The talented freshman waiting in the wings? That was Mobile’s AJ McCarron, who would eventually win two national titles as a starting quarterback for the Tide. But first, he had to wait his turn. Not always patiently.

I spent most of a full day with McCarron last week talking about the Tide’s most recent national championship, his future in the NFL and his memories of being a state champion at St. Paul’s and a three-time national champion at Alabama.

Among the topics he addressed on “Sports Drive” on WNSP was how close he came to seeing the first action of his college career in the 2009 national championship game win over Texas.

Junior Greg McElroy, who was suffering from a rib injury at the time, ultimately finished the game and a perfect season despite completing only six passes for a paltry 58 yards.

Watching his team struggle to try to throw the ball in the biggest game of the year, McCarron was in essence Tua before Tua.

“From what I heard from our coaching staff at that time, there were multiple weeks in a row that they were debating putting me in,” McCarron said. “I was told three weeks in a row that if we didn’t score coming out of halftime they were going to put me in. All three weeks we got the ball first in the second half and all three times we scored. So, I’ve definitely had that same type of experience before as Tua had.

“During the national championship game that year, I remember at one point I was warming up on the sidelines because Saban told me to get ready.”

McCarron now appreciates that he was able to redshirt that year, become a three-year starter and the winningest quarterback in Alabama history.

“As a competitor you want to play, it doesn’t matter when the opportunity comes,” he said. “But quarterback is just so different from every other position because only one guy can play at a time in a game. So any time you feel like you should be playing it’s because you’re a competitor. It’s a tough situation to be in. But from a coaching standpoint, you can’t really pull a guy who has led you to the national championship game the year before and you’re undefeated late in the season this year. So it’s really hard.”

Because of his experience as a player and his personal relationship with Saban, McCarron was not surprised to see Tagovailoa inserted into the game in place of starter Jalen Hurts.

“I figured something had to change at halftime,” he said. “Sometimes if you’re struggling on offense you just have to show you’ll take a shot down the field, even if you don’t complete it. We didn’t have that in the first half.

“Tua came in at quarterback and did an awesome job. I think Bama had been fortunate to not have gone against a team all year long that would make them throw the ball. It just so happened that in the national championship game that’s what happened and we finally had to make a change.”

The timing of the change was perfect, according to McCarron.

“Coming in at the half you at least have a chance to warm up,” he said. “As a backup it’s really better sometimes to say I’m just going to come out here and wing it and have fun.”

McCarron said he was as impressed as anyone with what he saw from Tagovailoa, and not just his physical skills.

“What he did on the last play was definitely rare for such a young guy,” McCarron said of Tagovailoa’s ability to look to his right in order to make the safety stay clear of where he planned to throw the ball down the left sideline. “It shows that his football IQ is very high. I thought he played great. But now every coach he plays against in the future is going to have tape on him and know how to attack him based on what he does well and what he might struggle with.”

Before Tagovailoa has a chance to live up to the ridiculously high expectations now being placed on his shoulders he’ll first have to prove he deserves to win the job over Hurts.

“I can assure you both guys will be given a chance,” McCarron said. “When you have more than one good quarterback you never know when your number is going to be called.”

Randy Kennedy writes a weekly column for Lagniappe and is co-host of “Sports Drive” every weekday from 3-6 p.m. on WNSP 105.5 FM, the country’s first all-sports FM station.