If there's one thing the New York Jets know about quarterback Sam Darnold, it's that he has the mental toughness to survive the NFL crucible. He proved it to the new regime in 2019, shaking off mononucleosis, a midseason slump and the fallout from the "ghost" game against the New England Patriots. He was mocked in two stadiums that shamefully played the "Ghostbusters" theme song, but he showed uncommon grit for a 22-year-old.

"Talk about toughness and talk about adversity," Jets general manager Joe Douglas said. "Not many guys faced more adversity than Sam."

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Douglas said it was "really impressive" to see how Darnold handled it, reinforcing the organization's belief that he has the right makeup to play quarterback in New York. Now comes the tricky part: As he looks toward his third season, the objective is to raise his tangibles as high as his intangibles. In other words, it's time to produce on the field.

While the basic data suggests the 2018 first-round pick made modest improvements in his second season, there's still not enough evidence on paper to say he will become an elite player at his position. There's a lot of stuff to be excited about, but he also has areas where he showed regression.

That Darnold was drafted by a perennial loser in the Jets exacerbated the typical growing pains. Unlike Baltimore's Lamar Jackson, Kansas City's Patrick Mahomes and Houston's Deshaun Watson, three of the four quarterbacks still alive in the AFC playoffs, Darnold didn't walk into a winning program with coaching stability. He has had it tougher than those peers, but the Jets' hope is that a full offseason with coach Adam Gase will allow him to take a big step in 2020.

"It will be huge," Darnold said. "Just stability and just continuing to build off what we've done this year, it will be huge."

Anyone can see he took small-to-medium jumps in the major statistical categories -- touchdowns, interceptions and completion percentage -- but sometimes you have to dig deeper to find answers. With help from ESPN Stats & Information and NFL Next Gen Stats, this is a next-level look at the positives and negatives from 2019 -- and a glimpse into what lies ahead:

Most encouraging signs

The biggest improvement for Darnold was his short-range accuracy.

As a rookie, he completed a league-low 59.1% of his passes in the 0-to-10-yard range (air yards), well below the NFL standard. It's hard to win games at that number. In 2019, his percentage soared nearly eight points to 66.9. That's still not a great number -- he should be in the 70s -- but it certainly showed the old-school cynics that, yes, a quarterback can improve his accuracy.

No doubt, Darnold benefited this season from the additions of wide receiver Jamison Crowder and running back Le'Veon Bell, proven short-area targets who combined for 144 receptions. Based on passer rating, Darnold went from 31st to 19th from this passing distance -- ratings of 73.7 to 86.1.

He made a similar jump against zone defenses (all distances). This was a bugaboo in 2018, as 10 of his 15 interceptions came against zone coverage. He ranked 32 out of 33 qualifying passers with a 71.5 rating. A lot of rookies struggle against zone because the coverages are more sophisticated than in college.

This season, Darnold did a better job of reading defenses and it showed. Only four of his 13 interceptions came against zone and his passer rating improved to 91.2 (19th). This isn't to say he has mastered the art of deciphering coverages. In the Jets' season finale, he was having trouble with the Buffalo Bills' schemes and asked Gase to spread out the defense by calling four-wide packages. The adjustment was made, and it gave him a cleaner look than before.

Statistically, Darnold also showed modest progression as a passer under pressure, although he still has a long way to go. He went from a horrible 33.2 rating to 48.3, which ranked 25th. He threw seven interceptions, tied with Los Angeles Chargers quarterback Philip Rivers for most in the league.

Considering the upheaval on the offensive line (nine different starting combinations), it's easy to assume Darnold faced constant pressure -- but that's not accurate. He was pressured on 29.5% of his dropbacks, virtually the same rate as in 2018.

Once again, his most memorable plays came outside the pocket, where he showed marked improvement. (Remember the dazzling touchdown pass to Crowder against the Baltimore Ravens?) His rating went from 54.0 to 78.0. Darnold's best attribute is his ability to make off-schedule plays, but you can't run an entire offense that way. What matters most is how a quarterback performs in the pocket.

Darnold made a negligible jump in that area (82.7 rating to 85.7) but not enough to satisfy Gase.

"That's something that we're going to keep working on, that's something that we can get better at," Gase said. "Sometimes he'll kind of escape the pocket on his own instead of working through the progression. That's sometimes what a young quarterback will do. I do think there were times where he did do a good job of staying in there and working through his progression in the pocket, but that's something that we can definitely work on this offseason."

Sam Darnold's 2018 vs. 2019 A statistical look at the New York Jets quarterback and his two NFL seasons: Year W-L Cmp/Att Pct. Yds YPA TD INT Rating QBR 2018 4-9 239/414 57.5 2,865 6.9 17 15 77.6 45.5 2019 7-6 273/441 61.9 3,024 6.9 19 13 84.3 41.5

Areas of concern

Quite simply, Darnold has to be better in the red zone. He threw four interceptions inside the 20 (tied with Chicago's Mitchell Trubisky for the league high) and ranked 32nd in passer rating (65.0).

No team can thrive when its quarterback is making critical mistakes in scoring territory. Remember the wet-bar-of-soap pass that was intercepted near the Miami Dolphins' goal line?

The numbers represent a significant drop-off for Darnold, who was surprisingly efficient as a rookie -- only one interception and a 95.7 rating. Gase has to take some of the blame because there was no offensive balance in the red zone, as the Jets ran a league-low 32 times. He relied too heavily on Darnold to make plays, causing him to press and make questionable decisions.

Darnold also suffered slippage in his medium-range accuracy (11-to-20 air yards), going from a 60.7 completion rate to 52.3. This one is hard to figure, especially since there was a small uptick in his percentage on long-range passes (21 yards or more). The decline could've been personnel-related, as the Jets lacked a consistent medium-range presence. It was an area where tight end Chris Herndon and wide receiver Quincy Enunwa, both limited to one game apiece because of injuries, would have helped.

Coach Adam Gase and quarterback Sam Darnold will have plenty to work on this offseason following the Jets' 7-9 season. Joshua Sarner/Icon Sportswire

Another puzzling decline was Darnold's performance against man-to-man coverage. Nine of his 13 interceptions came against some form of "man" coverage, basically a reversal of his 2018 trend. Weird, right? Specifically, he struggled against "Man-1" (one safety in the middle of the field), throwing six interceptions and five touchdowns.

Young quarterbacks usually fare better versus man than zone because it's a clean look -- i.e., less thinking -- but Darnold went against the grain in 2019. He'd probably help himself with better footwork. Despite constant emphasis by coaches, he still has a tendency to get sloppy with his feet, failing to set them to create a base. Sometimes he gets away with it, sometimes he doesn't.

For the second straight season, Darnold struggled against the blitz, finishing 32nd in passer rating (68.8).

Looking ahead

After some R&R, Darnold will begin his self-scouting process, breaking down cut-ups of every play from the season. He's also planning to work again with his California-based quarterback trainer, Jordan Palmer. By rule, he and Gase aren't allowed to meet until mid-April, when the offseason program commences.

"There are so many different ways you can break it down and see where my weaknesses were, and work on those," Darnold said of his tape study.

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He has a lot of positives to build on, but his game needs polish. The biggest thing is developing his pocket presence, which means learning to be patient but not to the point where he's hesitant to improvise outside the pocket. It's a delicate balance, one that requires reps to master.

The front office can do its part by improving the pass protection. Over the past two seasons, only five quarterbacks attempted more passes under pressure than Darnold, whose growth could be stunted behind a porous offensive line.

The Jets' 2020 schedule looks formidable and includes a handful of outstanding pass-rushing teams -- the Los Angeles Rams, San Francisco 49ers, Kansas City Chiefs and Denver Broncos among the non-divisional foes. The message is clear: Hire some new bodyguards for Darnold.

The organization is committed to Darnold, who has two years remaining on his rookie contract plus a team option for 2022. He played at a higher level toward the end of the season, after Gase streamlined the offense, and now they hope it can be a springboard into 2020.

"Sam and Adam formed a really strong relationship of open and honest conversation," Douglas said, "and I think you saw that kind of blossom through the end of the year."