Minicamp is mandatory (unlike OTAs), so it’ll be all hands on deck with all 90 players expected to be present.

Though technically not a part of the organized team activity schedule, few things are more organized than a Patriots practice, as the coaching staff squeezes out as much evaluation and teaching time as possible during the sessions.

The Patriots will take another step toward defending their Super Bowl title Tuesday when they kick off their annual three-day minicamp on the fields behind Gillette Stadium.

While the starters are pretty much established on both sides of the ball, there are questions to be answered, including the rotations at defensive end, linebacker, and nickel cornerback.


Additionally, the depth chart must be sorted out at several other positions (running back and tight end chief among them) as the staff looks to set the tone in preparation for summer camp.

Here’s a look at some of the key battles in the camp, which is not open to the public.

■ New England lost two veteran defensive ends who played pivotal roles last season. Chris Long (Eagles) and Jabaal Sheard (Colts) are gone, so there will be some healthy battles to earn playing time alongside expected starters Trey Flowers and Rob Ninkovich.

Veterans Kony Ealy (he’s looking for a bounce-back year) and Lawrence Guy (he has the versatility to shift inside) have the inside track, but they’ll be pushed by a trio of younger players, including a couple of rookies.

Geneo Grissom, who is entering his third season, was taking snaps over rookies Derek Rivers and Deatrich Wise during OTAs and will get his chances. Rivers, the team’s top pick (83d overall), and Wise (131st) will make strong pushes.

Rivers, a pass-rushing demon at Youngstown State (he owns the school record with 41 sacks), flashes excellent quickness and power.


Wise slipped through the draft cracks because of an injury-riddled senior season at Arkansas and could wind up being a fourth-round steal. He’s a relentless pursuer who collected 16½ sacks in the rugged SEC.

■ New England has one of the top linebackers in the league in Dont’a Hightower, and the corps surged late in the season when roles were firmly established for Shea McClellin, Kyle Van Noy, and Elandon Roberts. It didn’t hurt that wily veteran Ninkovich slid over to help stabilize the defense’s second level.

Depth was an issue, however, and undrafted rookie Harvey Langi was targeted to help address that. An athletic and adaptable player, Langi is a bit raw (he started his college career as a running back) and should benefit greatly from this week’s tutorial sessions.

■ At cornerback, Stephon Gilmore and Malcolm Butler have the starting spots locked down. Jonathan Jones, a special teams monster and one of the fastest players on the roster, was taking the nickel reps at OTAs, and it will be interesting to see whether the second-year player continues to do so over Eric Rowe and Cyrus Jones, who is looking for a fresh start after some rookie struggles.

Justin Coleman and undrafted rookie D.J. Killings, who comes in with a reputation as a quick player and a quick learner, also will be vying for spots.

■ Free agent signee Mike Gillislee would appear to have the inside track on the starting running back spot after ably serving as LeSean McCoy’s understudy in Buffalo. Gillislee is a sudden, one-cut runner who can take a hit and make extra yards.


Fellow free agent signee Rex Burkhead and the electrifying Dion Lewis will be in the hunt for snaps and carries, and it’s likely there will be plenty to go around as offensive coordinator Josh McDaniels looks to keep the legs fresh.

As for the third-down back, James White will look to build on what has been a steady progression through three seasons in New England. The man they call “Sweet Feet” also has sweet hands and continues to improve on his tackle-breaking abilities.

■ Brandin Cooks, Julian Edelman, and Chris Hogan are the established starters at receiver, but there’s a bevy of guys in town looking to get their hands on some of Tom Brady’s tosses.

Malcolm Mitchell is fresh off a solid rookie campaign and Danny Amendola’s toughness and clutchness can’t be dismissed despite his injury history. Recent signee Andrew Hawkins will give Amendola a fight to the finish.

Austin Carr, DeAndrew White, Cody Hollister, and Devin Lucien are looking at uphill battles to secure a residence in the locker room — though all are eligible for the practice squad.

■ If Rob Gronkowski and Dwayne Allen can stay healthy, there won’t be a lot of work for a third tight end (especially considering James Develin’s value), but that’s wishful thinking as this position takes a beating, so depth is exceptionally important.

Matt Lengel served ably as a backup to Martellus Bennett last season, and he and James O’Shaughnessy would appear to be the favorites for the third spot right now.


But this competition is far from over. Undrafted rookies Jacob Hollister (he’s athletic) and Sam Cotton (he’s a bull) will have a say in the matter.

. . .

The Patriots signed a draft pick, added an undrafted free agent, while releasing another.

Tackle Tony Garcia, the Patriots’ third-round pick out of Troy and the 85th overall selection, agreed to his deal monday.

The Patriots signed Will Likely, a defensive back out of Maryland. To make room, they cut Corey Vereen, a defensive lineman from Tennessee.

Jim McBride can be reached at james.mcbride@globe.com.