Elandon Roberts had the biggest hit of the day on the practice fields behind Gillette Stadium Sunday morning, but the linebacker was far from the hardest hitter on the field.

That honor probably had to go to a different kind of hitter – legendary boxer Marvin Hagler, who arrived at the conclusion of New England's fourth training camp practice and was scheduled to address Bill Belichick's team later in the afternoon.

Hagler spent time on the practice field chatting with owner Robert Kraft, Belichick and Tom Brady, among others. Apparently the defending Super Bowl champions have recently been watching footage of the former boxing champion's historic fights.

As for the action on the field, the second day in full pads, it was a bit more violent than Saturday's work. The practice included work with ball carriers being tackled to the ground by defenders, which doesn't occur all that often even in summer practice action.

The highlight of that tackling came on the goal line in 11-on-11 action. A day after Mike Gillislee punched in a pair of short touchdown runs, the defense put up a bit more fight. There was no better example of that than Roberts, who shot through the left side of the defense like a missile to tackle veteran back Brandon Bolden well shy of the end zone. It was an impressive play for the second-year thumper, who's always been better suited for physical action than the shorts-and-helmets work of the spring and early summer.

Overall Sunday included continued work on the running game in both half-line and team completion. Though the donning of pads the last two days hasn't brought quite as much energy as might normally be expected, the physical work in the running game has been noteworthy for players on both sides of the ball.

Besides the legendary boxer and the big Roberts hit, here are one man's Blogservations from the sun-soaked hill near the media tent:

--S Duron Harmon was absent from the practice field for Sunday's workout. The veteran suffered an apparent right leg injury late in Saturday's practice. The Boston Globe reported the injury is not serious and Harmon was with the rest of his teammates walking without obvious limitation at the retirement press conference for Rob Ninkovich later in the day.

--Ninkovich was indeed absent from the morning practice and announced his retirement from football at a 12:15 press conference. Seemingly the entire roster of Patriots attended the press conference, led by Tom Brady. Belichick, Kraft and Ninkovich spoke to the packed room of media, coaches and teammates.

--PUPers LB Dont'a Hightower and DT Alan Branch were on the field in sweats but retreated to do rehab work on the lower field during the practice. NFI rookie T Andrew Jelks did the same.

--WRs Danny Amendola and Malcolm Mitchell and DB David Jones were in full uniform/pads but also retreated to the lower field for rehab work and once again did not practice.

--Rookie WR Cody Hollister was not seen on the field after suffering an apparent left shoulder injury on Friday.

--There was a new WR/punt returner on the field wearing No. 16 in white. He could fill Ninkovich's spot on the roster, or come with another corresponding move.

--A day after he left practice early for unknown reasons, Bolden was back on the field in full pads and took part fully in the workout.

--Brady and Rob Gronkowski are far from the only ones who get loud cheers from the large training camp crowds in Foxborough. Jimmy Garoppolo got a pretty significant ovation as he walked up the stairs and onto the practice field on Sunday morning. Patriots fans seems to love their top two quarterbacks, which probably can't be said in almost any other NFL city.

--For what it's worth, as Garoppolo and Jacoby Brissett warmed up before practice James O'Shaughnessy stood next to Brissett to catch passes from Garoppolo while Austin Carr did similar duty next to the backup.

--While most players come and go via the stairs from the Gillette Stadium tunnel, there is also a back way on and off the practice field on the far end of the practice area. Brady often exits that way after workouts, while today Belichick and his assistant came onto the field via that more distant, private route.

--There was an interesting role reversal in the early pre-practice exchanges with the quarterbacks and centers. Brady actually got down and snapped the ball to James Ferentz, seemingly showing the backup exactly how he wanted the ball thrust upward/rotated on the snap. Brady probably snapped it to Ferentz a half dozen times quickly to get the offseason newcomer up to speed. There is no detail that Brady leaves up to chance or potential failure.

--Belichick spent a few minutes with 1-on-1 instruction with undrafted rookie linebacker Brooks Ellis in pre-practice action. The coach seemed to be instructing the Arkansas product on his coverage drops.

--For the third straight day the music leading off form running and stretching was Kenny Chesney's "Boys of Fall."

--The full-pads practice took place under sunny skies and temps in the 80s. The first four days of camp have included two pretty warm, sunny days sand two others, including yesterday, that were rather cool. The players can't complain about the weather to this point by any means.

--Kraft walked onto the field pretty early on in practice and watched the entirety of the workout before sharing some time with Hagler.

--The wide receivers worked on sideline catches as part of their positional work.

--During some early position group segments there was a group of core special teamers working together that included Jason Thompson, Nate Ebner, Matthew Slater, O'Shaughnessy, Joe Cardona, Jordan Richards, Brandon King and Jacob Hollister with special teams coach Joe Judge.

--At the end of the early practice group between the wide receivers and the defensive backs it was the group of receivers who were left doing pushups, a punishment after drills usually done by the coverage guys.

--Each day there is a drill with the defensive backs and pass catchers in which the receivers run down the field for deep balls from the quarterbacks. On some reps, the receiver lets up and the defender is supposed to make the interception. Other times through the line the defenders let up to allow the deep reception. Each morning this seems to catch the crowd off guard as they cheer the plays for the first couple reps before realizing how the non-competitive drill works.

--Brian Belichick is one of the Patriots coaching assistants this season. So far in camp the youngest Belichick has spent a lot of his work with his brother, safeties coach Steve Belichick. The latest Belichick to join the staff often is the one running the scout team cards/looks for his brother's group.

--Brissett and Rex Burkhead had to run a lap for a problem on a handoff in some early work in the running game.

--During some of the running game work it was interesting that fullbacks James Develin and Glenn Gronkowski were off on the far end of the field working by themselves and not included in the half-line action.

--The sun and heat weren't enough to warm up Patriots Character Coach/Team Development Jack Easterby as he wore sweatpants and a hooded sweatshirt with the hood over his head for much of the practice.

--Patriots video director Jimmy Dee had to go old-school and film some drills in the running game with a camera on top of a small step ladder.

--The pass catchers got the best of a bunch of 1-on-1 reps with the defensive backs. Carr beat Jonathan Jones, Dion Lewis had his way with Jordan Richards, D.J. Foster bested Thompson and Slater toasted Will Likely, except the captain actually dropped the pass.

--Chris Hogan also beat Dwayne Thomas on a deep ball, unfortunately the pass was overthrown by Brissett. As it hit the ground in front of the receiver Hogan kicked the ball onto the opposite field out of frustration.

--During the ball security drill with defenders trying to punch the football free while it's carried across the field O'Shaughnessy had a slight bobble while Dwayne Allen had it dislodged from his grip completely by Trevor Bates.

--Derek Rivers looked good as a blocker on the punt return team where he showed the ability to not only lock onto the coverage player but also to recover and regain contact after separation.

--After a rep in 1-on-1 pass rush work Kyle Van Noy had a little extra shove for rookie tackle Tony Garcia. The draft pick had done a nice job taking the veteran to the ground and Van Noy seemed annoyed by it and lashed out in minor fashion.

--Rookie defensive tackle Adam Butler beat Jason King on a nice speed move as an inside rusher. Despite a size disparity, Ferentz did a good job with Josh Augusta. Joe Thuney more than held his own against Trey Flowers.

--Judges' kids continued a camp tradition by working as ball boys and returning the football to Stephen Gostkowski after the kicker's field goals/PATs working by himself. One child even wore a No. 1 Patriots jersey with Judge on the nameplate.

--Jonathan Jones continues to get high level reps working in the slot with the group that includes Malcolm Butler and Stephon Gilmore. This trend continues after beginning all the way back to early spring practice.

--Brady completed a nice throw to a crossing Gronkowski in front of Richards. The completion was very much contested by the third-year safety, but the All-Pro tight end showed strong hands to bring the ball in and turn up field. It was the opposite result of a play on Saturday in the end zone where the two fought for the football to the end but the safety ended up with the pass defense.

--At one point in practice a small bird fought and harassed a much larger bird in the air above the practice fields. To put a new spin on the quote Patriots Hall of Fame running back Kevin Faulk was fond of saying: It's not the size of the bird in the fight, it's the size of the fight in the bird!

--Though he didn't get quite as many reps, Ryan Allen had a much better day punting the football. His first rep in team action was notable, as he turned over a pretty spiral for a long boot to Edelman.

--Deatrich Wise Jr. took another penalty lap and again did so at record-setting speed around the field.

--During one rep Brady and the rookie Carr were not on the same page, nearly leading to an interception.

--Harvey Langi continues to show the ability to play both inside and outside at linebacker, with many of the latter reps coming in a pass rush role.

--Wise Jr. sniffed out a screen and pulled down the running back for a loss on a pass from Brissett. The young backup probably would have been better off throwing the ball into the ground at his target's feet for an incompletion rather than losing the yardage.

--Late in practice the Patriots used a heavier front with Vincent Valentine at nose tackle, with Lawrence Guy to his left and Malcom Brown to his right. The look included Roberts and David Harris at linebacker over the guards.

--James White punched in a touchdown on the goal line, with Gronkowski landing a key block lined up out wide against the linebacker Van Noy.

--After getting blown up by Roberts on one goal line chance, Bolden followed his fullback Develin into the end zone for the score on another opportunity. Lewis knifed into the end zone on one of his chances. It looked like Foster lost control of the ball momentarily on a goal line run. Burkhead got stuffed by the defensive front.

--Dwayne Allen seemed to get a little shaken up late in practice. The tight end went to a trainer for some extra stretching, possibly on his lower back. He then skipped the tight end group's suicide sprints late in the day and walked a bit gingerly afterwards.

--Gostkowski hit all his PAT/short field goal attempts to close out practice.

--Kony Ealy, Brady and Kraft chatted for a couple minutes as a group during the special teams work.

--Ryan Allen punted to Cyrus Jones after practice. The returner continues to handle the ball well this summer.

--While the rest of the tight ends did the suicides, Gronkowski did pushups.

--After practice Brady did some extra work with Brandin Cooks and later Hogan and Edelman. The session of throwing was put on hold for a bit when offensive coordinator Josh McDaniels brought his family over to see the star quarterback.

--Ealy and Geneo Grissom stayed out late at the far end of the field to get some extra work in with the one-man sled.

--The Patriots will not practice on Monday, the first day-off of camp for the players. The team is scheduled to return to the field on Tuesday morning at 9:15 a.m.