[As a part of our partnership with ESPN, this story was originally published on ESPN+ and can be viewed in its entirety here with your ESPN+ subscription – NFL quarterback kryptonite: The biggest weakness for all 32 starters]

Even the best quarterbacks have problem areas. No signal-caller is perfect. And thanks to our advanced PFF data, we are able to identify those areas in need of improvement.

Utilizing the PFF play-by-play grading and everything else at our disposal from our ball-charting and QB accuracy numbers, we identified the biggest weakness for every starting quarterback across the NFL.

Weakness: Size

Only Andy Dalton has seen more passes batted at the line of scrimmage this season than Murray's four through two games. And he has targeted just four passes between the hashes, ranking 25th in passing grade on those targets. Murray's 5-foot-10 stature likely will continue to be a concern for Arizona's offense.

Weakness: Passes outside the numbers

Since the start of the 2017 season, Ryan ranks just 16th in passing grade on targets outside the numbers, despite having one of the NFL's top outside receiving targets in Julio Jones. Ryan has completed 67.2% of his passes targeted outside the numbers but also has made 12 turnover-worthy passes against 29 big-time throws — all of which are middling figures in the NFL.

Weakness: Accuracy

Jackson is the league's highest-graded passer through two weeks (91.2), but going back to his 2018 rookie season, when he made seven regular-season starts, he has thrown an uncatchable pass on 24.8% of his attempts, which ranks third-worst among quarterbacks with at least 150 pass attempts. But some optimism? Jackson's accuracy has improved drastically through two games this season, as he has thrown an accurate ball on 65.4% of his passes, sixth among starting quarterbacks.

Weakness: Accuracy

Allen has not been an accurate passer through 13 NFL starts, throwing an uncatchable-inaccurate pass on 25.2% of his attempts from the start of the 2018 season, the second-highest number in the league. Making matters worse, he has thrown the lowest percentage of perfect passes by our PFF ball-charting process, offloading one just 8.8% of the time.

Weakness: Accuracy

Newton has made an accurate pass on just 55.5% of his attempts since the start of 2018, the fifth-lowest mark among quarterbacks. And he has the league's second-highest catchable-inaccurate pass percentage — passes that are somewhat on the receiver's frame but still off-target in some direction — over the past two seasons. He has been reliant on receivers to make plays more than all but one other quarterback.

Weakness: Working to his next read

To be clear, Trubisky has struggled all over the PFF spectrum. But what really sticks out is his play while reading through his progressions. His 29.9 passing grade on second-read throws — throws made after the QB has clearly moved his eyes to his next receiver — is dead last in the NFL, and he has completed fewer than 50% of his attempts in those situations. His four turnover-worthy passes rank second-most since the start of 2018, and he owns the NFL's fourth-lowest adjusted completion percentage on his second reads.

Weakness: Downfield accuracy outside of structure

Dalton has struggled to make plays outside of structure. Since the 2017 season, he has the league's 24th-ranked grade on passes thrown at least 2.6 seconds after the snap (68.1) and ranks just 44th in completion percentage (49.7%) on such passes. With a porous offensive line, Dalton likely will have to deal outside of structure more often than most quarterbacks.

Weakness: Uncatchable passes

If there's one thing our reigning PFF Offensive Rookie of the Year needs to work on, it's cutting down on throwing uncatchable balls. Including his first two games this season, 18.9% of his passes have earned our uncatchable-inaccurate tag, which ranks 19th in the league over that frame. Mayfield has shown a high variance through his young career, placing balls perfectly 20.2% of the time — which ranks third in the NFL since the start of 2018 — while also throwing those uncatchable passes. When you have weapons such as Odell Beckham J.r and Jarvis Landry, all you have to do is make the passes catchable.

Weakness: Uncatchable passes

Prescott has been accurate to start the 2019 season, but if last season is any indication, he probably will regress to being more of a middle-of-the-pack quarterback in our accuracy charting. In 2018, Prescott saw just 61% of his passes deemed accurate, while 19.6% of his passes were deemed inaccurate and uncatchable, the 10th-highest rate. Avoiding that will only mean good things for the Cowboys in 2019.

Weakness: Too aggressive, too passive

During Flacco's Baltimore tenure, he was certainly too aggressive at times, uncorking big-time throws at will but adding several turnover-worthy passes at the same time. But through two games with Denver, he has unleashed just two big-time throws and is seeing an average depth of target of just 6.4 yards downfield. He also has two turnover-worthy plays. Flacco has become too passive in his game while trying to avoid turnover-worthy passes.

Weakness: Inconsistency

Stafford has never really been able to back up elite-level performances for an entire season. Just last season alone, he put forth two elite game grades but followed those two matchups with three game grades lower than 57.1. He has finished with middling grades in seemingly every season of his career, and now Stafford owns the league's third-lowest adjusted completion percentage through two games in 2019.

Weakness: Holding on to the ball too long

Rodgers not only set the record for most throwaways in the PFF era last season — he shattered it. Of his 597 total attempts in 2018, Rodgers threw away 59 passes, 19 more than any other quarterback. Part of the reason? He holds on to the ball far too long. Rodgers has thrown the second-most turnover-worthy passes on passes thrown longer than 4.1 seconds after the snap since the 2018 season.

Weakness: Intermediate accuracy

Watson's accuracy on passes targeted between 10 and 19 yards downfield is certainly a glaring concern. Since the beginning of the 2018 season, Watson ranks just 36th among quarterbacks to attempt at least 25 passes to the intermediate area of the field, throwing an accurate pass on just 43.3% of his attempts.

Weakness: Lack of big-time throws

In his lone season as the full-time starting quarterback for the Colts, Brissett was ultraconservative with the football, unleashing a big-time throw on just 15 attempts, a figure that ranks outside of the top 50 among all quarterback seasons since 2017. He also had 12 turnover-worthy passes that season.

Weakness: Arm strength

Minshew hails from Washington State's Air Raid, a QB-friendly system. He rarely had to fit the ball into tight windows downfield, but his arm strength will be tested with the Jaguars. Minshew has attempted just five passes 20 or more yards downfield, and two of those attempts were classified as inaccurate-uncatchable passes. Additionally, he completed fewer than 50% of his attempts targeted 20 or more yards downfield and outside the numbers, which are passes that require elite-level arm strength.

Weakness: Turnover-worthy plays

With big-time plays come the propensity to increase your turnover-worthy plays. Mahomes led the league with 46 big-time throws in 2018, but he also had 19 turnover-worthy passes — the ninth-highest single-season total from any quarterback over the past three seasons.

Weakness: Turnover-worthy plays outside of the numbers

No quarterback has thrown more turnover-worthy passes on throws targeted outside the numbers than Rivers over the past two seasons. His 22 such throws on 479 attempts leads all NFL quarterbacks. On the bright side, he has seen only 14 of those passes actually intercepted.

Weakness: Passes outside the numbers

After a dismal rookie season, Goff has tightened up seemingly all of his weaknesses. But if one still remains, it's his play on throws targeted outside the numbers. Since the start of the 2018 season, Goff holds the league's 18th-highest passing grade on throws targeted outside the numbers and has thrown 19 turnover-worthy passes on such attempts, the sixth most in the span.

Weakness: Accuracy

Sure, Rosen was under pressure a lot during his first season with Arizona, but his overall accuracy percentage on his passes of 57.1% was dead last in the NFL a season ago. Making matters slightly worse was the fact that his 55.2% accuracy percentage when he was kept clean from pressure was the third-worst in the NFL, while 22.6% of his pass attempts from a clean pocket were deemed inaccurate and uncatchable, the third-highest rate from starters in the league last season.

Weakness: Red zone grades

Ranking just 14th in passing grade on throws inside the opponent's 20-yard line, Cousins has struggled with his red-zone play over the past two seasons. His five turnover-worthy passes on throws inside the red zone doesn't sound like a high number, but consider that it ranks as the 11th most among all quarterbacks since the start of the 2017 season, while his four interceptions are the sixth most.

Weakness: Passing grade on second-read throws

It's a hard task to find Brady's biggest weakness, even at age 42. But he hasn't been great on second-read throws of late, even though it's relative for him. He still ranked ninth in passing grade on second reads (76.4) last season, completing 58% of those passes to rank outside the top 20. (However, his numbers over the past three seasons in those categories put him in the top three among signal-callers.)

Weakness: Too conservative

In his full season as the starter for the Vikings in 2015, Bridgewater finished with a strong PFF passing grade but was much more conservative than Saints fans are certainly used to from Drew Brees. Bridgewater averaged a depth of target just 7.5 yards downfield, tying for the shortest average depth of target among all quarterbacks in the NFL that season and he uncorked just the 19th-most big-time throws.

Weakness: Turnover-worthy passes

Jones was the draft class' 23rd-ranked quarterback by passing grade on passes targeting receivers at least 20 yards downfield. He completed just 11 of 45 deep passes, which was the fourth-worst among all 45 qualified quarterbacks available in the 2019 NFL draft. In the preseason, when the buzz started to build around Jones, he threw an accurate deep ball 42.9% of the time, ranking 10th among the 51 quarterbacks who attempted at least five deep attempts.

[Editor's note: This story was published prior to the announcement that Daniel Jones would start for the Giants in Week 3]

Weakness: Downfield passing

The new Jets starter finished the 2018 season with just a 79.0 passing grade on passes targeted 20 or more yards downfield, ranking 27th among the quarterbacks in his draft class. And his adjusted completion percentage on deep shots in his final collegiate season was just 41.1%, ranking outside the top 15 among draft-class quarterbacks.

Weakness: Second-read throws

Buying time in the pocket and working through progressions is pivotal for any NFL quarterback, and unfortunately for Raiders fans, it's also something Carr has struggled with over the past few years. Since the 2018 season kicked off, his 34.5 passing grade on his second read is the second-lowest grade in the NFL, and his four turnover-worthy passes on such throws are the second most.

Weakness: Turnover-worthy passes

From the start of the 2017 season, Wentz has done a lot right. But he also has unloaded a ton of turnover-worthy passes. His 28 such throws rank as the 13th most among all signal-callers since the beginning of the 2017 season. Wentz has gotten a bit of interception luck, as only 16 of those have actually been picked off, but we'd still like to see that number decrease for him to crack the top tier of quarterbacks.

Weakness: Making plays late in the down

Rudolph will certainly be tested as he takes over for Ben Roethlisberger. One thing he struggled with during his time at Oklahoma State and in his limited duty so far in the NFL is his ability to make plays outside of structure and if the play breaks down. Through two preseasons with the Steelers, Rudolph finished with a 54.3 passing grade on his second-read throws, a figure that ranks 40th among the 51 quarterbacks with at least 10 pass attempts on their second read. He is an athletic player, so if he can maneuver his way around the pocket to buy time, he should do just fine in the Pittsburgh scheme.

Weakness: Passes 20+ yards downfield

Jimmy G has not seen a full season as a starter, so we have to look into the whole big picture with him to find the biggest weakness. He has attempted just 34 passes at least 20 yards downfield since the 2017 season, and of those, 20.7% have been deemed catchable-inaccurate passes. Worse, another 37.9% are considered uncatchable-inaccurate attempts. When you have downfield threats such as Marquise Goodwin, you have to be able to hit your mark on those passes.

Weakness: Too many sacks

Wilson has brought harm upon himself far too often, playing behind a poor offensive line for a good part of his NFL career. But he invites pressure by holding on to the ball too long, and our grades have him responsible for 13 sacks and 34 total pressures last season.

Weakness: Forcing too many throws

It's no secret to even the most casual of fan that Winston forces the ball at times. He does have a high incidence of positively graded plays, but forcing the ball into tight windows — windows he shouldn't even attempt to throw into — has seen him finish with near-league-high figures in percentage of negatively graded plays in each of his four full seasons. Since Winston entered the league in 2015, only Eli Manning has thrown more turnover-worthy passes (97) than Winston's 90.

Weakness: Pocket presence

For such an athletic player, Mariota struggles to find a rhythm in the pocket. He takes off more than most, scrambling out of the pocket on 63 attempts since the 2017 season, the sixth-most scrambles among all quarterbacks. He has invited 12 sacks on his own over that time span as well, finding unnecessary pressure far too often.

Weakness: Turnover-worthy passes on deep balls

Even with his career year in Minnesota in 2017 factored in, Keenum has thrown the third-most turnover-worthy passes targeted at least 20 yards downfield since 2017. His adjusted completion percentage of just 41% and an accuracy rating on deep shots of 34.4% over that time are both bottom-tier figures among quarterbacks.

Read More PFF Analysis