A day after Tom Brady and Rob Gronkowski treated training camp like their personal game of catch, the defense exacted a measure of revenge on Friday. While it would be foolish to suggest there was anything wrong with the best passing duo in the NFL, things weren't quite as smooth for the offense in general on Day 2.

One reason for that may have been the conditions, which were much more stifling on Friday than a day earlier. Bright sunshine and humid temperatures seemed to take a toll on the field as several players appeared to be affected.

The only player who didn't make it through practice was Marcus Cannon, who left about midway through with head trainer Jim Whalen. It was unclear what led to Cannon's departure, but he walked slowly with Whalen and did not appear to be limping in any way. ESPN.com reported there were no long-term concerns and that he could return as early as Saturday, which would be an indication that the heat played a role.

LaAdrian Waddle took Cannon's place at right tackle for the remainder of the practice.

Several others were slow getting from drill to drill as practice wore on, and perhaps that was one reason for the less-than-stellar production of the passing game. Brady misfired on a couple of throws, one over the head of Jordan Matthews near the right sideline during an 11-on-11 drill. He also failed to connect with Julian Edelman when his pass was knocked away on a terrific play by Stephon Gilmore. Gilmore's leaping over-the-shoulder deflection was reminiscent of his fourth-down play that clinched the AFC title game win over Jacksonville in January.

But Brady made his share of throws too. He connected with Matthews on a back shoulder fade in the end zone behind Ryan Lewis, and later found Cordarrelle Patterson, who made an excellent one-handed grab over Gilmore, for another touchdown.

All in all the pace seemed to slow a bit, which given the heat and the fact that the team will be in pads on Saturday for the first time was understandable.

"We knew the weather going in and we keep ourselves hydrated. That's just part of camp," running back Jeremy Hill said. "Our second game is in Jacksonville, so, you've got to get used to it now."

"Yeah, sun was out today, but it wasn't too, too bad," added guard Joe Thuney. "The wind was blowing. Just tried to push the fluids, keep hydrated."

In addition to the heat and some of the offensive struggles, here are one man's blogservations from Day 2 of training camp in steamy Foxborough:

-There was some good news on the injury front as Brandon Bolden, who opened camp on the non-football illness list, was back in uniform and took part in practice. Also, Malcolm Mitchell was briefly in uniform and took part in warmups before removing his No. 19 jersey and heading to the rehab field. It was the first time we've seen Mitchell this season, and given the fact that he reportedly underwent a procedure on his knee earlier in the week it was noteworthy that he wasn't wearing a brace of any kind.

-Elsewhere on the medical front, the list of players on PUP remained unchanged. Matthew Slater, Jonathan Jones (Achilles), Cyrus Jones (ACL), Nate Ebner (ACL) and Kenny Britt (hamstring) were not in uniform but all took part in warmups before joining Mitchell on the lower rehab field. All did plenty of running and did not appear to be moving at less than full strength, which could be an indication that their returns might be sooner than later.

-The Patriots made a roster move after practice, signing wide receiver Paul Turner and releasing tight end Troy Niklas. Turner was an undrafted rookie in 2016 and spent most of the year on the Eagles practice squad. He played in four career games and has nine catches for 126 yards -- all in 2016. He was released by the Eagles last summer and was out of football before signing a futures contract with New Orleans, but the Saints cut him June 21.

-For the second straight day Bill Belichick went right from his on-field press conference before practice to the conditioning hill for some running. He spent a few minutes there, alternating forward and backward runs up the hill as he continues to working in his 44th NFL season.

-Former Patriots wide receiver Tiquan Underwood was on hand to watch practice. He spent some time with receiver coach Chad O'Shea and later chatted with Belichick before he was greeted by many of his former teammates at Rutgers including Britt, Duron Harmon and Devin and Jason McCourty. Underwood is now the wide receivers coach at Lafayette.

-Another former Patriot, long snapper Lonie Paxton, took in practice from the friends and family tent. He later spent some time with Brady and Stephen Gostkowski in the field after the workout.

-As practice began the three kicking specialists – Gostkowski, Ryan Allen and rookie Corey Bojorquez – retreated to the rehab field to begin their work. The returned shortly after and resumed their kicking with the rest of the team.

-For the second straight day the defensive linemen worked with martial arts expert Joe Kim at the start of practice, doing drills refining their handwork and other techniques. Later in practice Dont'a Hightower got some one-on-one time with Kim during a special teams period.

-Joe Judge has a growing stable of what has seemingly become special teams only players (beyond just the specialists). Slater is the most celebrated of the group, but in recent years players like Ebner and Brandon King have fallen into that category as well. It looks like Nicholas Grigsby might be added to that list. Grigsby is listed as a linebacker on the roster but spends significant time working with Judge during team periods. On Friday he and King joined Judge on the left field while the offense and defense worked on the right. Earlier in practice, Keion Crossen, A.J. Moore and Eddie Pleasant did a drill where they raced around a hoop and kept low as they turned, reaching down to grab a towel before ripping through as they made their way upfield.

-Rex Burkhead continued his trend of wearing white shorts. He was the only players donning the white once again on Friday. Not sure if it's related but the running back has looked especially quick in the early going of camp.

-During a ball security drill one of the first players to take a rep was Dwayne Allen. The tight end ran between two tacklers and wound up knocking one of them – Deatrich Wise – off his feet. It was a strange sight considering the drill doesn't generally involve any contact, but Wise nonetheless ended up on the ground.

-Speaking of Allen, Friday may have been one his best practice days as a receiver since joining the team last year. He made a handful of tough grabs, one an impressive snag with his arms stretched out wide of his frame to haul in a slightly overthrown ball. Allen drew praise from coaches last year for his blocking but provided little as a receiver. On Friday he flashed as a receiver, which could be an indication that he's more comfortable in the offense and ready to take on a bigger role, which is something he talked about wanting during the spring.

-On the flip side, Jacob Hollister did not enjoy a strong day. The tight end had at least two disappointing drops and was visibly frustrated with himself. He's had a strong start to the 2018 season with a solid spring and good first day, but Friday was not his best effort. Still, he will be in the mix for the backup tight end role this year.

-Jason McCourty took some reps with Gilmore, Harmon and his brother during an early seven-on-seven drill. It was the first time I could recall seeing him with the front line players since he joined the team. When play shifted to full team work, he went back to the second group but he is getting more reps now that camp has opened. He seems to be doing well with those reps as well. He showed strong coverage working against Chris Hogan on a deep ball in the end zone, knocking Brian Hoyer's pass away despite wearing the makeshift boxing gloves the DBs often don during camp.

-The special teams focus on Friday was on the punt team as Allen and Bojorquez alternated kicks. Both kicked the ball well with one glaring exception when Bojorquez delivered an epic shank that wobbled out of bounds on the left sideline barely 10 yards downfield. Otherwise, both punters had solid efforts.

-With Ebner on PUP, Jordan Richards and Burkhead took turns as the personal protector. On the outside, Patterson and Crossen made up one pair of gunners while Matthews and Pleasant represented another group. Patterson and Matthews were noteworthy as players vying for secondary receiver roles looking to provide special teams value as well. Patterson is obviously a kickoff return candidate but he also has experience as a gunner.

-During the special teams work, Gronkowski, Hogan, James White and Phillip Dorsett got some work in with the quarterbacks and offensive coordinator Josh McDaniels. Dorsett was mainly a downfield option last season but has worked in the slot much more often thus far in camp and has impressed. His presence working with Brady has to be a good sign for the 2015 first-round pick.

-Kyle Van Noy is another player who has been active in the early going. The linebacker has been excellent in coverage during the first two days, especially on Friday. He did a great job working against James White, leading to a pass breakup in the end zone when White could get position on the linebacker. He also had another pass defensed on a crossing route when he dropped into a zone to prevent a completion. He's looked quite speedy during the first two days.

-Gostkowski got some field goal work in late in practice, working with Bojorquez as his holder. Allen handled those duties on Thursday and neither punter appeared to have any issues as Gostkowski has kicked the ball extremely well at the start of camp.

-Rookie Isaiah Wynn was forced to run a lap late in practice due to a false start. He continued to work at left tackle with a group that included Ted Karras at left guard, James Ferentz and Luke Bowanko alternating at center, Jason King at right guard and Ulrick John at right tackle.

-Hoyer struggled for most of the day, particularly late when running the two-minute offense. For the most part, his group continued down the field only due to the scripted nature of the plays because many of his passes fell incomplete. Earlier he was late with an out route in the end zone and JC Jackson easily undercut the receiver and picked it off. Hoyer did drop a beautiful pass into Edelman's arms for a touchdown, showing excellent touch well perfectly placing the ball over the receiver's shoulder.

-Those speaking to the media after practice included White, Devin McCourty, Gronkowski, Gilmore, Trent Brown, Hollister, Thuney, Hill, Van Noy, Karras, Gostkowski, Elandon Roberts and Riley McCarron.

-The Patriots will be back at it on Saturday for their first full pads practice of the summer. The workout is open to the media and will get underway at 9:15 a.m. on the practice fields behind Gillette Stadium. Please check patriots.com for any last-minute schedule and weather-related updates.