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When it became apparent really isn't important.

It might have been apparent way back in March, when the Raiders were studying quarterbacks in the draft. After witnessing Derek Carr's impressive workout at Fresno State, the Raiders put him first on their quarterback board, ahead of Blake Bortles, Teddy Bridgewater, Johnny Manziel and the rest, according to offensive coordinator Greg Olson. The team valued Carr as a high first-round pick, but it did not value him more than linebacker Khalil Mack. So the Raiders chose Mack with the fifth pick of the first round.

Then, with the fourth pick of the second round, the Raiders jumped.

"All the things we were looking for in a quarterback, we felt he had," Raiders general manager Reggie McKenzie said in a post-draft press conference.

It was starting to become apparent in the months between the draft and the start of the regular season. At his first practice of the offseason, Carr was a presence, Olson said, encouraging teammates and showing leadership and maturity in a manner that is uncommon for rookies. Already married for two years and a father, there was nothing about Carr that indicated he was only 23.

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They weren't wearing pads or playing with pass rush in May and June, but Carr impressed the coaches with his decision-making, quick delivery and accuracy. He was supposed to be outperformed by Matt Schaub and Matt McGloin, but Olson said Carr consistently graded the highest of the group. Then, in training camp, the somewhat puzzling trend continued.

He started slowly in the preseason and didn't play in the important third game with a rib injury. But in the finale, then-head coach Dennis Allen started Carr against the defending champion Seahawks. In a little more than one quarter against Seahawks starters, Carr threw three touchdown passes and was the primary reason the Raiders won 41-31. That was all Allen needed to see to make a bold move.

It was becoming apparent to some people in the first weeks of the regular season. In his debut against Rex Ryan's complicated Jets defense, Carr did not turn the ball over, and he had a 94.7 passer rating.

Against the Texans the following week, he caught the eye of Patriots coach Bill Belichick. On one play, Carr faked a handoff left, then sprinted to the open field to his right, outrunning several defenders for a 41-yard gain.

"There are not a lot of quarterbacks in the league that would make that play," Belichick told reporters at the time. And he added, "I think the kid's got a great future."

It became apparent to a lot of fans on a Thursday night versus Kansas City in late November. The Raiders still were winless and had little reason to believe they could change that against a 7-3 team that was coming off a victory over the Seahawks.

"There was a lot of pressure on his shoulders when you haven't won a game at that point in the season," Olson said.

He did not play like it. The Raiders trailed the Chiefs by three when they took over at their own 20 with 9:03 remaining. Sixteen plays later, Carr had the Raiders on the Kansas City 9-yard line. As he took his place in the gun, he told Bleacher Report he recognized the Chiefs were playing a type of Cover 0 without blitzing. The key, though, is there was no safety in the middle of the field.

Carr walked back to the center, changing the protection. Then, with the crowd roaring, he signaled to his receivers by putting his hands up next to his ears and shaking them.

Carr called for wide receiver James Jones to run an out and up toward the middle of the field, the soft spot in the Chiefs' coverage. Jones easily shook safety Ron Parker, and Carr lobbed it to him in the back of the end zone for what turned out to be the game-winning touchdown.

"It was a relief to get that first win under my belt," Carr said. "To be able to do it that way, make a check, throw it to James for a touchdown, it couldn't have been written any better."

Now people were beginning to see why Jones had been calling Carr "Baby A-Rod," since he had worked out with him when Carr was at Fresno State. Jones thought Carr reminded him a little of the guy who used to throw him the ball when he was in Green Bay.

The play also underscored the fact the Raiders have not had to dumb down the offense much for the rook.

"He's extremely intelligent, so he handles everything at the line of scrimmage," Olson said. "We've given him the freedom to…get us out of bad plays. He's been able to do that, change protections, change routes at the line of scrimmage. We're not trying to hold him back."

It was becoming apparent even during some low points, like the Raiders' 52-0 loss to the Rams the week after the Kansas City win. In that game, Carr threw two interceptions and was replaced by Schaub in the fourth quarter. The move really wasn't about performance, though. Somewhere along the line, Carr had become too important to the franchise for an interim head coach to risk getting him injured in a meaningless blowout.

"The organization understands," Olson said. "There is no playoff berth we're playing for. It's important to try to win a game, but it is more important to make sure Derek is continuing to develop. You know there is something special here in the future, and the Raiders haven't had that for a long time. As bad as this season has been, there is a silver lining here."

Derek Carr week-by-week Week Cmp-Att Yds TD-Int Rating 1 20-32 151 2-0 94.7 2 27-42 263 1-2 69.8 3 21-34 174 0-1 62.6 4 16-25 146 1-1 76.4 6 18-34 282 4-1 107.7 7 16-28 173 0-0 75.4 8 34-54 328 1-0 86 9 24-41 194 2-2 66.5 10 30-47 192 2-2 68.8 11 16-34 172 0-0 62.4 12 18-35 174 1-0 75.2 13 24-39 173 0-2 50.5 14 22-28 254 3-0 140.2 15 27-56 222 1-0 64.7 16 17-34 214 2-0 89.6 pro-football-reference.com

Some coaches would have preferred to sit Carr if they had been in charge of the Raiders. There is little reason to believe the fields behind the Raiders' Alameda facility have fertile soil for quarterback growth. Carr doesn't have a true No. 1 wide receiver or a tight end who forces game-plan adjustments, and the Raiders' running game statistically is the least effective in the NFL. Yet Carr has thrown more completions than all but two rookies ever. With 25 more against the Broncos on Sunday, he will set a record.

"We decided playing would be the best teacher for him," Olson said. "It's never been an issue of trying to take baby steps. Our quarterbacks coach, John DeFilippo, has done a good job with him. There were some things he did early on where you would grit your teeth a little. Without experience, it was tough for him to understand the concept or reason behind it. But he's a quick study. He's become more and more comfortable with the reasons why he's doing things."

Despite the circumstances, Carr was ready to be developed.

"The best way for me to learn and help this franchise go in the right direction is to let me get out there and learn from experience," he said. "Right now is obviously a hard time, probably the hardest time I'll have to deal with in my career. To get through this and know better times are ahead, there is a lot of confidence building."

Carr acknowledges the losing has been difficult, as was seeing Allen fired. By many accounts, however, his confidence has not been diminished.

There have been rumblings that interim head coach Tony Sparano was considering benching Carr at times. CBS broadcaster Phil Simms told the Raiders coaches he thought Carr should be replaced the day before Carr's first victory against the Chiefs, according to Olson. But Olson said it never has been a possibility because the coaching staff saw consistent improvement from Carr, as well as an unbroken spirit.

That does not mean Carr has arrived. He still is trying to figure out the most important thing of all—how to win the game. Olson wants to see more improvement from Carr at pushing the ball downfield. He ranks 32nd in the NFL in yards per attempt, but he is working at it.

"He has to create explosive plays," Olson said. "That's a critical part of his growth."

It had become apparent even to skeptics during the Raiders' 24-13 upset of their Bay Area neighbors in early December. In that game, Carr outplayed Colin Kaepernick, threw three touchdowns and completed 78.6 percent of his passes, but it was the subtle aspects of his play that were most impressive.

In the third quarter, the Raiders were trailing by three. On a 2nd-and-7, Carr dropped back and looked for fullback Marcel Reece on a little curl, but Reece was covered. He progressed to tight end Mychal Rivera. Didn't see an opening. Then he looked for wide receiver Kenbrell Thompkins on a crossing route. Nothing there.

Finally, he turned to wide receiver Andre Holmes, his fourth read, running a comeback on the sideline. Carr fired the pass before Holmes came out of his break. The completion went for 16 yards and was the key play in the touchdown drive that put the Raiders ahead for good.

"You can see him go one, two, three, four, release, and watch his feet and eyes work together," Olson said. "It's not just going through progressions, it's the understanding of the timing of progressions. It's one of those plays you would put on your clinic tape. This is the timing you want on this play, this is what it is supposed to look like."

On a third-down play when the 49ers sent seven rushers after Carr, he calmly checked down to Jones. He didn't get the first down, but he did the right thing.

By this game, Carr was more comfortable with the speed and timing of the NFL and knew more on what he could and could not get away with.

"Coming from college and going to the NFL, the speed isn't even close," he said. "At first that was an adjustment. Now I'm getting used to it."

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Growth also was evident in Carr's drops, his patience in the pocket and his understanding of individual matchups. And, perhaps most significantly, Carr was proving he could take a hit in the pocket.

In the fourth quarter of the win over the 49ers, Carr faced a five-man rush from shotgun. Justin Smith got a push up the middle to close in on Carr, and Aldon Smith slashed across the line and flashed toward him as he threw. Carr took a big hit from Aldon Smith that left him on the ground, but he got the ball off to Rivera for a 27-yard gain.

Now this—this—was a sign of development for Carr. It is wonderful that his 2.0 interception percentage is seventh best in the NFL, that his red-zone passer rating is 97.8 (according to STATS), and that he performed better Sunday against the Bills defense than Peyton Manning and Aaron Rodgers did in the previous two weeks.

But what is really significant for Carr is that he is proving to be tough in the pocket. The pre-draft knock, according to a number of scouts, on Carr was the hits would get to him. His last college game at Fresno State, a loss to USC in the Royal Purple Las Vegas Bowl, left a bad final impression as he struggled to set his feet and deliver with authority as the Trojans pass rush closed on him.

Carr probably would have been chosen well before the Raiders took him in the second round if teams thought he could consistently make the type of throw he made to Rivera.

"People didn't question my knowledge, my throwing ability or athleticism; they questioned my ability to stand in and take a hit," Carr said. "So to be able to answer those questions on a week-to-week basis has been pretty cool."

Olson said the most significant area of Carr's growth has been becoming more comfortable in the pocket under pressure. "He does not look scared in the pocket," Olson said.

Carr has found courage through knowledge. His understanding of protections, which may be unprecedented for a rookie quarterback, has given him peace of mind.

Carr often knows where pressure may be coming from because he has been studying protections since most kids were studying fractions and decimals. When Carr was in sixth grade, he and his family moved from California to the Houston area, where they could watch Carr's brother David play for the Texans after they had made him the No. 1 pick in the 2002 draft.

David would take Derek to the Texans locker room. Derek says they would talk football and watch tape. David showed Derek why he was on his back so much.

They had a lot to talk about. David was sacked 76 times in his rookie year, an NFL record. Three years later, he was sacked 68 times, third most in NFL history. Derek, meanwhile, has been sacked only 21 times this season. According to Pro Football Focus (subscription required), he has been sacked on 9.5 percent of the snaps he has been pressured—best in the NFL among players who have taken at least 60 percent of their team's snaps.

It is as if David took the lumps so Derek wouldn't have to.

"When I got here, I had already seen these blitzes and pressures," Derek said. "Having a big brother who taught me protections and blitz recognition has helped out a lot."

When it became apparent really isn't important. But it has become very apparent that the Raiders should be out of the Marcus Mariota-Jameis Winston discussion.

Carr arguably is the most promising of all the vaunted rookie quarterbacks. And for a franchise that knows not where home will be, or who will be putting the playbook together, Derek Carr is the cornerstone to build on.

Dan Pompei covers the NFL for Bleacher Report. Follow him on Twitter @danpompei