NFL minicamp primer: Brady, Gronk back on practice field

More than three months remain until the start of the NFL season, but something significant changes with the offseason over the next two weeks. Specifically, this is when things get mandatory.

Four NFL teams -- the Bears, Lions, Dolphins and Patriots -- will hold their mandatory minicamps this week. The other 28 teams will hold theirs next week. Unlike organized team activities and early offseason workouts, all players under contract are expected to be in attendance. Missing mandatory June minicamp can result in fines of about $14,000 per day up to three days.

So while guys like Tom Brady and Rob Gronkowski in New England, Julio Jones in Atlanta and Aaron Donald in Los Angeles have been able to skip their teams' offseason programs so far, they need to show up for work this time around or else it'll cost them.

(Note: This does not apply to a player such as Pittsburgh's Le'Veon Bell, who has been designated the Steelers' franchise player but has not signed his franchise tender, which means he's not technically under contract. Because he's not under contract, he does not have to attend mandatory minicamp.)

What can players do? Not a lot more than they could in OTAs. Still no shoulder pads, still no contact allowed. They can run 11-on-11 drills in which quarterbacks throw to receivers and defensive backs can cover, but there's no blocking, no all-out pass-rushing and definitely no tackling allowed. Teams can hold two practices per day for three days, so long as the players aren't on the field for more than a total of 3.5 hours per day and the second session is a walk-through.

So what you have here are practices that start to LOOK like training camp but are still a step behind it in terms of intensity. Coaches will get to see how players are functioning and understanding their assignments in their respective offenses and defenses, how healthy their key players are (Deshaun Watson? Andrew Luck? Odell Beckham Jr.?) coming off injuries and maybe set their depth charts for training camp. A player can show enough in this minicamp to help his chances of opening training camp as a starter at his position.

It's about learning for the players, and about assessing for the coaches. For us fans, it's about feeling just a little bit closer to the start of the season.

Chicago Bears

Biggest storyline: The Bears' season revolves around quarterback Mitchell Trubisky. Coach Matt Nagy has gradually asked more and more of Trubisky throughout the voluntary offseason program. Chicago's ability to contend in the NFC North hinges mainly on Trubisky's mastery of Nagy's offense -- the same scheme used in Philadelphia and Kansas City -- but the second-year quarterback is light on experience. The key for Nagy is finding the perfect balance for Trubisky, who started only one full year at North Carolina before the Bears drafted him second overall in 2017. The Bears went to great lengths to upgrade their offensive supporting cast, but Trubisky's performance supersedes every other storyline.

On the mend: The Bears expect the prominent trio of wide receiver Allen Robinson, outside linebacker Leonard Floyd and right guard Kyle Long to be medically cleared when training camp opens on July 19. But all three could play a role in mandatory minicamp. Both Robinson and Floyd took part in OTA drills last week -- their first on-field action of the offseason -- and Long spent one week of OTAs lining up with the first team without a helmet. The Bears are counting on Robinson and Long to help Trubisky on offense. Floyd is one of Chicago's top pass-rushers, but durability has been a concern since the Bears took him in the first round of 2016. -- Jeff Dickerson

Detroit Lions

Biggest storyline: Learning the defense is going to be the main focus for the Lions all the way up to the season opener in September, and a three-day minicamp is a chance to further refine what they've started. A lot of the installation thus far has been basic, but that figures to change as Detroit maneuvers through its spring practices. It'll also be the first time the Lions have a chance to get a feel for what their full defense could look like, since safety Glover Quin has skipped voluntary workouts thus far this offseason but should be at minicamp next week.

Offensive wrinkles: Matthew Stafford is at the nitpicking stage of his career, particularly within Jim Bob Cooter's offense. Stafford understands the big picture of what's supposed to happen and has thrived in the system installed at the start of the 2016 season. That said, Cooter said any changes made won't be drastic but that there is a lot of carryover from prior years. Cooter wouldn't get into details, but three straight days of watching Detroit's offense -- even in a limited form without pads -- should start to give a clue as to what the Lions might be trying to change this season. -- Michael Rothstein

Miami Dolphins

Biggest storyline: Whether the Dolphins can bounce back from a 6-10 finish in 2017 will depend largely on how quarterback Ryan Tannehill fares in his return from a knee injury. "We're going to go as far as he takes us," defensive end Andre Branch said, according to the Miami Herald. It will be worth watching during minicamp how Tannehill develops chemistry with a group of new targets, including wide receivers Danny Amendola and Albert Wilson, as well as tight end Mike Gesicki. Tannehill has been fully participating in organized team activities after his injury.

Tracking Minkah Fitzpatrick's fit: The Dolphins opted for the best player available when they took Fitzpatrick at No. 11, but he joined a position of lesser need at safety. How Fitzpatrick fits alongside incumbent starting safeties Reshad Jones and T.J. McDonald is something to continue to monitor. "I think that we can all make it work," McDonald said about the logjam at safety, according to the Palm Beach Post. "However it works out, it'll take care of itself." One possibility is the Dolphins use a 4-2-5 package as their base defense, according to the South Florida Sun-Sentinel, allowing them to keep all three safeties on the field. -- Mike Rodak

New England Patriots

Biggest storyline: Welcome back, Tom Brady and Rob Gronkowski. The two captains haven't been participating in the Patriots' voluntary offseason program, but owner Robert Kraft said he expected them both to be present at mandatory minicamp. When coach Bill Belichick has been asked about Brady and Gronkowski in OTAs, he's deflected, saying he will talk about the players who are present. The dynamic will be altered in minicamp, which is essentially an extension of OTAs. Both players have some ground to catch up on, and it will be notable to see where they fall in line from a repetition standpoint (first unit, second unit, etc.). Said linebacker Dont'a Hightower, "We'll be glad to have them both, but it's not going to stop us from working."

Big week for receivers: Outside of Julian Edelman and Chris Hogan, the Patriots' wide receiver corps has a group of players who could benefit from time developing a connection with Brady because of their lack of familiarity with him, and so this will be the first chance for the likes of Jordan Matthews, Cordarrelle Patterson and rookie Braxton Berrios to do so. Also, Kenny Britt and Phillip Dorsett fall into a similar category of not having a deep background with Brady because they joined the Patriots during the 2017 season. So this is a week in which a small part of a foundation could be laid. -- Mike Reiss