FOXBOROUGH, Mass. -- Ever since tight end Rob Gronkowski announced his retirement in late March, the hot-button question has been how the New England Patriots will reshape their attack without him.

Josh McDaniels, the architect of the ever-evolving unit, keeps reminding everyone that he doesn't have the answer right now. He isn't being evasive as much as highlighting what has made the Patriots one of the most unique offenses in the NFL: a rare adaptability.

Last season, when the Patriots transformed to a smash-mouth approach in mid-December en route to their sixth Super Bowl championship, is a classic example of it.

"There are still a lot of unknowns, still a lot of bridges you have to cross, a lot of reps we need to take and get better at and improve on," McDaniels said as the 2019 preseason ended. "There are areas of the game that we will continue to improve on and develop our identity and our team over the course of the regular season, which will be a lot more telling than what I know at this moment."

Specific to personnel, McDaniels obviously knows more now than he did in spring practices and training camp.

Four-year veteran Matt LaCosse (career-high 24 catches in 2018) and 2018 seventh-round draft choice Ryan Izzo (rookie season on injured reserve) are the lone tight ends. Veterans Benjamin Watson (four games) and Lance Kendricks (one game) are serving NFL suspensions to open the season.

Fullback James Develin, who played 35% of the offensive snaps last season, also factors significantly into the mix. Even when Gronkowski was on the field last season, and wasn't often at his peak, Develin became a huge part of the attack.

This was a notable part of NFL Films' "Do Your Job" special (NFL Network, 8 p.m. ET Wednesday) on the 2018 Patriots -- how the offense turned to an old-school formula to turn its season around after back-to-back December losses to the Miami Dolphins and Pittsburgh Steelers.

"One of the things that I'm so thoroughly impressed with Bill [Belichick] on is his ability to adapt and evolve. He said, 'If you keep holding on to what [you'd] rather be -- no-huddle, spread formations, 34 points per game -- then you're probably going to end up regretting a lot of things at the end of the year. What are we really good at? What's the most consistent part of our team offensively?' Then you commit to it," McDaniels said in the special.

"We had been a pretty decent running football team. It was something we felt our personnel fit. It's going to be the I-formation, running a lead play, gaining 6 yards, line up and do it again. You have to be content saying, 'I'm going to try to win this way, because this is the way we can win.' I think our team really embraced that. We were adaptable."

The Patriots will take the same adapt-on-the-fly approach in 2019, hoping for similar continuity on the offensive line -- even though that has already been tested with the loss of starting center David Andrews (blood clots in lungs) for the season. Also, 2018 first-round pick Isaiah Wynn steps in at left tackle in place of Trent Brown, who signed with Oakland in the offseason.

The Patriots appear to be deeper than ever at running back with Sony Michel, James White, Rex Burkhead, rookie Damien Harris and Brandon Bolden, which could spark more confidence in the ground game.

And Super Bowl LIII Most Valuable Player Julian Edelman leads a wide receiver corps that also includes Josh Gordon, Demaryius Thomas, Phillip Dorsett and undrafted rookies Jakobi Meyers and Gunner Olszewski, with first-round pick N'Keal Harry opening the season on injured reserve.

One point running backs coach Ivan Fears made was that the direction of the offense -- from a fullback-led, grind-it-out approach to more of a spread passing game -- will be dictated by what the Patriots see from defenses.

"Depending on how people play us, it can be more [running] or less. You can load the box up with so many guys that it's just not good. You're trying to throw the ball because there are too many guys in the box to run the ball," he said. "Or you can play it too light like the Chargers did [in the AFC divisional round], and all of a sudden we're going to run the ball against you."

The Patriots have long had such flexibility in their Tom Brady-led attack, with perhaps the lone exception coming in the 2007 season, when they were so dominant throwing the ball to Randy Moss, Wes Welker, Jabar Gaffney, Donte' Stallworth & Co. that they basically stuck with that regardless of what the defense did.

It was the opposite of the run-based approach at the end of the 2018 season.

"I don't think too many people worry about the fullback in the game the way people are playing now, with all the spread offense, the explosive offenses," Fears said. "They think of this as 2 yards, a cloud of dust, and here we go. You just have to make them pay."

McDaniels said the basic principles for his offense are taking care of the ball, reducing penalties and keeping mistakes to a minimum. That's pretty much Offense 101 across the NFL.

It starts there, but there is so much more for him to learn as the season progresses.

"To say exactly what we're going to be, what groupings we're going to lean on, who's going to play this many snaps, the roles everybody has ironed out yet, it would be unfair for me to say that," he said.

As McDaniels said in the "Do Your Job" special: "Tom, if he’s supposed to hand it off 37 times and win that way, then he'll do it. If we need him to throw it 52 times, then he'll do that, too.

"It's the same way Bill is. Bill doesn't care if we have to win 43-40 or 13-10. The willingness to be able to do that is really a special trait."