The last time Tom Brady had to learn a new offense, the tablets he and his teammates currently study on were still 10 years away from their invention. It was the first year of the new millennium, and Tristan Wirfs, Tampa's first-round pick and rookie right tackle, was just a year old.

After 20 years on the same job working for the same boss, Brady admitted to reporters last week that he'd forgotten how intense that learning process was. 

"It's been different having the opportunity over this time to move and to, for example, study my playbook—I mean I really haven't had to do that in 19 years, so you forget, 'Man, that's really tough,' like all of the different terminologies," Brady told reporters last Thursday. "You're going back a very long time in my career to really have to put the mental energy in like I did."

Overwriting 20 years' worth of data is no small feat. Brady was so comfortable in New England's system that he skipped out on the voluntary offseason workouts the last two years, the only quarterback in the league to do so both seasons. Not so in Tampa. As a Buccaneer, Brady has time-traveled back to be an eager rookie again, ignoring public health guidelines to work out at a public park in Tampa, and accidentally breaking and entering a home he thought belonged to his new offensive coordinator Byron Leftwich.

Without a formal offseason program, Brady's task is even tougher. What exactly is on his plate right now with Arians' offense? Former Cardinals quarterback Carson Palmer knows the challenge of mastering an Arians offense well. "I don't know how many different offenses I had to learn throughout my career," said Palmer, who played in Arizona for Arians during his first head coaching gig, from 2013 to '17. "But [Arians' offense] is by far the most challenging. There are so many different formations. There's different shifts, there's different adjustments. It is a little bit easier on the skill-position players, receivers and tight ends and backs, because it is all the same concepts, but anybody can really run each position. Everybody is interchangeable, and you have to know when a halfback is running a certain route or a receiver or a tight end or a guy that is not used to running that same route."

Arians is known for his love of the deep ball and "home run" plays with longer-developing routes, but he's said his concepts aren't much different from Brady's New England experience. "[Brady] is a very bright guy, so the playbook is just learning a language," Arians said during a post-draft media availability. "It's so similar to what he's been with the last 20 years. It's just what we call it. We have time to collaborate on, 'All right, give me your 10 best,' 'This is what our guys can do,' 'This is what we'll call it'—so it's just names. That part of it will just take time."

For Palmer, the biggest adjustment was learning Arians' terminology for defensive coverages. "I have always called defensive coverages the same thing throughout my career and he had a totally different way," Palmer said.

Early in their time together in Arizona, Palmer said Arians kept calling a specific defensive coverage, "Cover 5." Palmer had never heard that term before, nor had any of his Cardinals teammates, who were also new to Arians' coaching. "What the hell is Cover 5?" Palmer remembers everyone thinking at the time. "Does he not know what he's talking about?"

He and Arians had several back-and-forth arguments about Cover 5, only to realize each time that they were talking about the same thing, a man-to-man type of coverage, but using different words. "That drove me nuts," Palmer said. "All of his defensive terminology threw me at first. We would get in these knockdown, drag-out arguments and then realize like 35 seconds in the conversation we are both talking about the same thing. … So yeah, that's gonna be really tough on Tom unless Tom is of that verbiage from New England."

And with 45 years of coaching experience, Arians is firmly set in his ways. "I realized right away, he was not going to change," Palmer said.

It's possible Brady and Arians have already had their own version of the Cover 5 argument.

Arians told reporters last week that he shows Brady no special treatment, and Brady, "gets cussed out like everybody else."

In five seasons under Arians, Palmer said he never felt totally comfortable in the offense, at least not in the way that Brady described not having to devote much mental energy to studying his playbook with New England. "No, never," Palmer said. "Because it evolves. This is year one, and Bruce has been enough places where he has a style and system that he uses in year one. He will add another 20 percent next year and then probably another 30 percent the following year. He is really just in the phase right now where they are trying to see what everybody can handle. What is too much? What is not enough?"

For his part, Buccaneers lead running back Ronald Jones II said he hasn't noticed Brady struggling to learn the new terminology. "I wouldn't even know," he told B/R in a video call with reporters. "None of the guys would know either that he was having to learn. He hasn't missed a beat. He hasn't misled anybody on a play or things like that, so you wouldn't even know obviously with his resume. It's good to be out there with a guy like that, a real field general."

In a late July interview with reporters, Arians said that Brady was "way ahead of the curve" with mastering his offense. The Bucs head coach has always been a collaborative leader, working with his quarterbacks to incorporate their favorite plays and what they can do best, and he said he'll do more of that this season to lighten the load for Brady. "It's a dual thing," Arians said. "Him learning what we do, me learning what he likes. Meeting in the middle and doing a lot of different things. I'm not going to ask the other 21 guys to learn something new when they've already had a good year and good experiences in the offense."

Hall of Fame quarterback (and Brady's own childhood hero) Joe Montana is the easiest comparison to Brady's career path. But when he was traded to the Chiefs after 13 seasons and four Super Bowl victories with the Niners, Montana didn’t have to start over completely. Paul Hackett, his quarterback coach from 1983-'85,  went with him and took the job as Kansas City's offensive coordinator.

"The plays were a lot of the same," he said during a media appearance promoting Guinness beer's partnership as the official beer of Notre Dame alumni and fans. "Some had new twists in them, but for the general guts of the offense, if you looked at the drawings, you would see the plays of what we ran in San Francisco when Paul was there. It certainly was a lot easier for me having someone who understood what I did."

The biggest challenge, Montana said, was dealing with the high expectations in joining a new team at age 37 after a storied career in San Francisco. "Probably just getting over the nervousness of going into a new locker room," he said. "Even with the success you had, they want to see if you are going to have similar success with them. ... As soon as that happened, everything fell into place after that."

Tampa Bay brought back backup quarterback Blaine Gabbert after he spent most of 2019 on injured reserve. He also played for Arians in 2017 in Arizona and said he's been serving as a sounding board for Brady whenever he has questions about the terminology for the progressions and protections.

"Any time I can help make things easier or relate his questions, because going from a system he has been in for 20 years and now having to learn a new one, there are a ton of questions that we have," Gabbert said. "And with such a condensed training camp schedule, we are behind the eight ball."

Leftwich also played quarterback in Arians' system during his NFL career, and Gabbert said his experience seeing the game through a QB's eyes is valuable for their group. Early on, Brady appeared to be picking things up smoothly, Gabbert noted, but added that missing out on the offseason program robbed the six-time Super Bowl winner of the chance to get in much-needed repetitions with his new teammates. "We usually install our system a few times by training camp," Gabbert said. "Go through it once, go through it twice throughout OTAs and minicamp."

Said Palmer: "Aside from COVID, that is their biggest challenge, is that lack of time. The good thing is, all these veteran teams who aren't young and these veteran QBs, they have a huge advantage over these QBs like [Bengals quarterback Joe] Burrow, who are going to be expected to play year one, and the guys in developing years two and three, like the Baker Mayfields."

Time is a crucial factor this season. What Brady lacks in real time to perfect a new offense before the season starts, he should be able to make up for in historical time and experience. That should help when he faces those Cover 5 defenses.

Kalyn Kahler covers the NFL for Bleacher Report. Follow her on Twitter for NFL musings and weird quarantine thoughts: @KalynKahler.