No NFL roster is perfect. Every team has an area on the depth chart that it wishes were deeper or a position that lacks starting-caliber talent and/or experience. 

But some roster holes stand out more than usual, particularly if they could serve as an Achilles' heel for a contending team. 

Here are particularly glaring roster holes that could impact eight teams expected to be in the mix in 2019. 

New England Patriots Tight End

Did you hear? Future Hall of Fame tight end Rob Gronkowski retired from the New England Patriots, and it doesn't look as though he's on the brink of a comeback. 

Even in a relative "quiet year" last season, Gronk had 682 receiving yards and was a huge factor during New England's Super Bowl run.

The Patriots signed the talented Austin Seferian-Jenkins as a potential replacement, but they released him while he deals with what NFL Network's Ian Rapoport reported were "personal issues." They signed veteran Ben Watson, but the dude is 38 years old and will serve a four-game suspension after testing positive for a banned substance. They traded a conditional 2020 seventh-round draft pick to the Detroit Lions for Michael Roberts, but the 2017 fourth-rounder has just 13 catches in two seasons. 

That probably means some guy named Matt LaCosse will be New England's starting tight end in Week 1, which is far from ideal considering that the 26-year-old has caught 27 passes in a four-season span with the Giants and Broncos since going undrafted in 2015.  

The Pats have a special way of finding and grooming talent, but the tight end position appears to severely lack talent heading into training camp. And that could be a problem for soon-to-be 42-year-old quarterback Tom Brady, who no longer has a top-notch arm and could use a reliable safety valve beyond Julian Edelman. 

Houston Texans Left Tackle

Houston Texans franchise quarterback Deshaun Watson took a league-high 62 sacks last season, and left tackles Julie'n Davenport and Martinas Rankin were big reasons for that. Among 85 qualified offensive tackles at Pro Football Focus, both ranked in the bottom 10, and Davenport surrendered a league-high 66 pressures.

The team brought in Matt Kalil this offseason, but the 2012 No. 4 overall pick out of USC hasn't been effective since his Pro Bowl rookie season with the Minnesota Vikings, and he's coming off a major knee injury. The Texans also drafted potential future starting tackles Tytus Howard and Max Scharping in the first two rounds, but both players could need time to develop. That's not a luxury the win-now Texans have at the moment. 

Houston had to do more to secure Watson's blind side. The team was leapfrogged by the Eagles in the first round of the draft for highly touted tackle prospect Andre Dillard, but well-established veteran Donald Penn remains on the open market. He should be a candidate to at least attempt to plug a dangerous hole in 2019.

Otherwise, it's fair to wonder if Watson will have enough protection to take the next step in his critical third season with a team that is looking to win playoff games in 2019.

Baltimore Ravens Edge-Rusher

Three members of the Baltimore Ravens had six or more sacks last season, but two of those pass-rushers— Za'Darius Smith and Terrell Suggs—are gone. That leaves Baltimore to test out a variety of outside linebackers this offseason, but none inspires tremendous confidence for a team that often either prospers or dies on defense. 

Fourth-year fifth-round pick Matt Judon has become a solid player on one side and could have a chance to build on a seven-sack 2018 season, but beyond that, it's disappointing 2017 third-round pick Tim Williams (two sacks in two seasons), free-agent pickup Shane Ray (two sacks the last two seasons in Denver), 2017 second-rounder Tyus Bowser (3.5 sacks in two pro seasons) and rookie third-round pick Jaylon Ferguson (who requires time and development). 

Jeff Zrebiec of The Athletic reported in March that Ravens head coach John Harbaugh has challenged both Bowser and Williams to rise to the occasion in 2019, and Bowser seems to think he's ready to take off. But for now, the Ravens lack established talent at a key position. And that could make it just a little bit harder to support raw, young franchise quarterback Lamar Jackson in 2019. 

Jacksonville Jaguars Tight End

The Jacksonville Jaguars have a shiny new quarterback named Nick Foles, but have they surrounded him with enough talent? 

They at least have receivers and running backs (Dede Westbrook, Marqise Lee, Leonard Fournette) who have high ceilings and have flashed at the NFL level, but the tight end position looks like a gaping hole entering training camp. 

That was also the case last year after Seferian-Jenkins went on injured reserve with a core muscle injury in October, but the cap-strapped Jags didn't retain ASJ and weren't able to make any splashes at that position this offseason. That leaves them with James O'Shaughnessy, Geoff Swaim, Ben Koyack and Josh Oliver.

Among 44 tight ends with at least 20 catches in 2018, O'Shaughnessy ranked 43rd with 8.9 yards per reception. Swain didn't fare much better in that category (ranked 36th) and is coming off a four-season run in Dallas in which he scored one touchdown.

Koyack has five catches the last two seasons, and Oliver is a rookie third-round pick who Bleacher Report draft expert Matt Miller believes is merely suited for "a backup or complementary role."

Tight end Zach Ertz was Foles' favorite target the last two years in Philadelphia, but the 30-year-old veteran might not be able to rely much on his tight ends in Jacksonville. That could make it harder for the Jags to come out on top in the super competitive AFC South.

Oakland Raiders Edge-Rusher

Maybe the Oakland Raiders aren't on the brink of a championship season, but they have a Super Bowl-winning head coach and a three-time Pro Bowler at quarterback. So with the right support, there's always a chance they could do some damage. 

The problem is it'll be tough for the defense to fully support Derek Carr's offense, thanks mainly to a lack of teeth on the edge. 

That's been a problem ever since the Raiders traded away Khalil Mack, who registered nearly as many sacks in 2018 (12.5) as the entire Oakland defense (13). To put that into more perspective, no other team in the NFL had fewer than 30 sacks on the season. 

But despite having oodles of money to spend, the Raiders essentially neglected the defensive end position in free agency. While other teams added key pass-rushers Trey Flowers, Dee Ford, Justin Houston, Alex Okafor, Ziggy Ansah, Za'Darius Smith and Preston Smith to the fray, Oakland signed...Benson Mayowa!

They'll be hoping that 2018 third-round pick Arden Key and rookie No. 4 overall selection Clelin Ferrell can make major impacts, but Key had just one sack despite playing every game as a rookie, and Ferrell was widely considered to be a reach in that spot. 

The Raiders might again have the worst pass rush in the league, which makes their entire defense a liability.

Seattle Seahawks Safety

The Legion of Boom has quickly become ancient history in Seattle, where the Seahawks are rebuilding their defense but have yet to find replacements for legends Earl Thomas and Kam Chancellor. 

Bradley McDougald is a decent player coming off a three-interception year, but he's never been in a Pro Bowl conversation in six NFL seasons, and a balky knee continues to give him trouble. That's what made it so odd that the Seahawks didn't touch any free agents at that position. 

They did use a second-round pick on Utah product Marquise Blair, but Matt Miller sees Blair as more of a special teams player early in his NFL career, and he's also been injured this offseason. 

The only other somewhat established player the Seahawks have at safety is Tedric Thompson, who was often invisible unless he was missing tackles in 2018. 

Safety might not be a premium position, but the Seahawks built a miniature dynasty there. Now a competitive Seattle team is exploitable in the secondary thanks mainly to a lack of talent in those two spots.

Dallas Cowboys Safety

But the Seahawks aren't the only 2018 playoff team that is glaringly short on talent at the safety position, because the Dallas Cowboys continued to neglect that spot this offseason.

As a result of not drafting a safety until Round 6 and barely investing in the position on the open market, the Cowboys look as though they'll be rolling with Jeff Heath, Xavier Woods, George Iloka and Kavon Frazier as their top four safeties in 2019.

Put simply, that's ugly. 

Heath and Woods had a combined three interceptions and two forced fumbles as full-time starters last year, and according to PFF, only one NFL safety missed more tackles than Heath. The 28-year-old isn't a starting-caliber player, but Iloka barely saw the field last year in Minnesota, and Frazier has done nothing in three seasons to indicate he should play a larger role. 

The rest of the defense is in good shape, but for the team to finally make a deep playoff run, it'll have to overcome two noticeable holes on the back end of that defensive unit. 

Tampa Bay Buccaneers Running Back

Maybe new Tampa Bay Buccaneers head coach Bruce Arians is enough of an offensive mastermind to fix the Bucs' running game without any significant personnel changes. But until Arians gets results, that position will continue to look like a potential Achilles' heel for an otherwise talented team. 

Lead back Peyton Barber ranked 40th among 49 qualified players last season with a 3.7 yards-per-attempt average, and that rate shrank to 3.3 in the final six games. But 2018 second-round pick Ronald Jones II was even worse. In fact, the USC product was basically unplayable. 

Since the 1970 AFL-NFL merger, 270 running backs selected in the first or second round have carried the ball at least 20 times as rookies. Among that group, only Jones averaged fewer than 2.0 yards per attempt. While his 23-carry sample was small, he also rushed for just 22 yards on 28 attempts in the preseason. 

There's hope the USC product will turn it around in year two, but that's far from guaranteed. Barber clearly isn't the answer, but the Bucs have nobody else. They're gambling on Arians and those two players at running back, which could backfire by leaving quarterback Jameis Winston high and dry far too often.