Here are four things we've learned so far before the team takes the ice for its first preseason match.

"I want to see them applying some of the things we've been working on, the different steps with and without the puck," Vigneault said after Day 3.

On the eve of the Flyers first preseason game, the team has already been through three days of practice. The pace has been exceptionally fast. The real test, however, will come in game action. Head coach Alain Vigneault has specific things he's looking for in the exhibition games on Monday, Tuesday and Thursday.

PUSHING THE PACE LIKE NEVER BEFORE

One thing that has been a constant through the first three days of practice has been the breakneck pace of the drills; there has been almost immediate turnaround from one drill to the next with almost no time spent huddled around a coach at the dry erase board at center ice.

Each day, there is pre-practice meeting to describe the drills and their purpose. Video teaching is emphasized before the players get out on the ice. From there, the pace has moved extremely rapidly. Additionally, each day, there has been a 5-on-5 competition component with two forward lines and two D pairs taking alternating reps against two opposing forward lines and D pairs.

"We've looked at different things. We looked at our D zone coverage and our NZ forecheck. [On Saturday], we touched a little bit on our OZ forecheck. We've touched on all three zones without the puck. [On Sunday], we're going to touch a little bit more on play with the puck," Vigneault said after Day 2.

Indeed, on Day 3, there was a lot of work done on breakouts and entries on the offensive side of the puck and on back pressure without the puck. At Monday's morning skate in Voorhees, the team will spend 25 minutes working on the power play.

Once the season starts, Vigneault plans to keep morning skates to a minimum.

"I'm not a big morning skate guy," he said on Sunday.

Something else that has stood out early in camp: On Day 1, 2, or 3 of many NHL training camps, it is still common to see a segment of practice devoted to goal line-to-goal line sprints. Vigneault has not done them. He said on Sunday that he believes players get more conditioning wise from the ultra fast-paced game-situation simulations that have been common early this camp, and it also reduces the chance of players suffering groin pulls early in camp during the skating drills.

ONE LINE QUICKLY CLICKING

The big standouts on Saturday's first session was the line trio of James van Riemsdyk, Kevin Hayes and Oskar Lindblom. They had a solid day together on Friday as well, but were notably dominant on Saturday in 5-on-5 drills. Even the defense pairing of Travis Sanheim and Philippe Myers had a hard time containing the line in the attack zone.

"I've really liked that line. I've liked the way Kevin Hayes has worked and led his two linemates, both with and without the puck. We wanted to get a look at Oskar on the right side. We're probably going to try him there during exhibitions," Vigneault said.

On Sunday, Jakub Voracek was moved onto the Hayes line, while Lindblom skated left wing with second-year pro German Rubtsov and veteran tryout Chris Stewart as his linemates. Vigneault indicated after Sunday's practice that the day's lines would remain together for Monday's game.

"They're a heavy line with Oskar there, and even heavier with Jake. We'll take a look at that in the first game," Vigneault said.

However, the coach said that Lindblom would subsequently get opportunities in camp to play on the right side again with Hayes and JVR.Video: Hayes, Myers and Vigneault speak after training camp

THE BLUE LINE BATTLES

So far at least, it appears that Ivan Provorov and Matt Niskanen will be a pairing on defense, as will Shayne Gostisbehere with Justin Braun. Travis Sanheim skated with Philippe Myers on Day 1 and Day 2 of practice, and with Robert Hägg on Day 3. Samuel Morin was with Andy Welinski on Sunday.

As of now -- and this could certainly change if Morin steps up as camp progresses -- the battle for the sixth starting spot on defense appears to have Myers and Hägg as the top two contestants.

On Sunday, Vigneault was asked about his observations on Myers in camp after coaching him on Team Canada at the 2019 IIHF World Championships.

"He's looked real good. He's got size. He's got mobility. Good puckhandling skills and a good shot. He's one of our top prospects. Hopefully, with the right attitude on his part and good development on ours, he can become a real good player for us," Vigneault said.

THE CHALLENGE ... AND REWARDS

Flyers general manager Chuck Fletcher said on the first day of camp that the top skill-player prospects would get a chance to play with -- and against -- the top veteran skill players in camp. The team has done exactly that.

Joel Farabee spent Day 1 and Day 2 of camp on the top line with Sean Couturier and Claude Giroux. Morgan Frost and Isaac Ratcliffe skated with Jakub Voracek on the first couple days. On Day 3, the trio of Ratcliffe, Frost and Farabee were back together as a line, and they will start together on Monday in the exhibition opener.

Farabee has hit the ground running immediately, not just holding his own but excelling in drills. He's looked very much like he did in Rookie Camp, pressuring the puck on the forecheck, finding the seams and being in the middle of scoring chances for whatever linemates with whom he's played.

Couturier said of Farabee, "He's been great. Fun to play with. Smart player, good skills. I like the way he thinks the game. He knows what play to make, even before getting the puck. That's good for a young player to adapt like that, especially at this speed."

The one question with Farabee is sustainability at this age. Is he ready to do what he's done so far for the duration of camp? Can he do it not just early in the regular season but continue to do it over an 82-game slate without "hitting the wall" by midseason?

Couturier said of Farabee, "He's been great. Fun to play with. Smart player, good skills. I like the way he thinks the game. He knows what play to make, even before getting the puck. That's good for a young player to adapt like that, especially at this speed."

A fascinating scene unfolded in the Group A session on Saturday afternoon. Throughout the five-on-five drills, Vigneault had the line of 20-year-old Ratcliffe, 20-year-old Frost and veteran Voracek go head-to-head against Giroux, Couturier, and 19-year-old Farabee.

Frost held his own in some early reps, but then Couturier turned things up a half-notch and dominated rep after rep on both sides of the puck. Ratcliffe got schooled repeatedly by Giroux. On one particularly notable rep, Ratcliffe skated through the neutral zone with the puck and had his pocket picked cleanly by the Flyers captain.

With a half grin, Vigneault admitted after Day 2 practice that he had put kids in the deep end of the pool by design.

Said Vigneault, "I mentioned it to Lappy [assistant coach Ian Laperriere] when we were standing at the net, 'Those two kids are learning the NHL pace there.'"

Frost was a little bit downbeat after practice. He knew the competition bar had been set as high as it could get -- no matter how long he plays pro, he'll never face matchups that get all that much tougher than going up against a bigger, stronger, much more experienced Selke candidate who is also an NHL 30-goal scorer.

"It was a little overwhelming, to be honest, to play against guys that caliber. I felt like I was just watching, chasing the puck all day. I'll try to learn from them, and do better the next time," Frost said.

Couturier showed some good leadership after practice. He publicly put out some soothing words of encouragement for Frost, and reflected back on his own first NHL camp when Peter Laviolette put him out against NHL stars Giroux and Danny Briere and then had him go head-to-head with other teams' veterans in road exhibition games.

"It can intimidating. You can be impressed and kind of shy almost to play. But you've gotta just play, be yourself. Push to make plays, be the player you are," Couturier said. "[Frost] was a high pick and he had a lot of success in junior. I think he's ready for the next level. He's got to go out, just play and show it."

There was nothing to be ashamed of. Frost competed -- as did Ratcliffe -- and fared significantly better in Days 1 and 2 than at the same juncture of camp last year. They've seen where they'll need to get to in order to become the top-six caliber NHL players that the organization believes they can develop into. They will still get preseason game action to show if they can translate their Rookie Camp and Rookie Game dominance into high-level performances at the preseason NHL intensity level and pace (i.e., things crank up higher in the regular season).

On Sunday, the reunited Ratcliffe- Frost- Farabee line went up against third-year pro Mikhail Vorobyev centering a line with Kyle Criscuolo (an established AHLer with 9 games of NHL experience) and rookie pro Maksim Sushko. On this day, the battle was much more even in terms of which line won the mini-battles that took place between the whistles.

Frost won some; including successfully pulling off one of his Ontario Hockey League signature moves -- a toe-drag and quick shot -- and beat NHL roster defenseman Shayne Gostisbehere and goalie Brian Elliott to score a goal. The move elicited some oohs and ahs from the fans in the stands. Against the 6-foot-2, 214-pound Vorobyev, Frost didn't dominate but he also didn't get dominated. It was more evenly matched, and it also challenged Vorobyev to push himself in the battles. The Russian forward, who opened last season on the NHL roster, gave a solid account,

Another rookie vying for an NHL spot in camp is German Rubtsov. With less fanfare than some of the other high-end draftees in both Rookie Camp and NHL Camp, the 21-year-old Russian has been very solid both at center and right wing.

Vigneault said of Rubtsov, "I saw him in the Rookie Game. I think he has good pace to his game and good hockey sense. He's playing with two good players [Lindblom and Stewart in Monday's exhibition opener] and it'll be fun to see what he can do."

Last but not least, it should be noted that even prospects who are not realistically in the running for an NHL roster spot out of camp but who are competing hard and effectively have seen the opportunity to be rewarded.

On Sunday afternoon, second-year pro David Kase skated with Couturier and Giroux as his linemates at practice. This was clearly a way for the coaches to say they've noticed that the 22-year-old Czech winger had a solid Rookie Camp, Rookies Game and worked his tail off in the 8:30 a.m. "C" group on Day 1, and as part of a line with Rubtsov and second-year pro Connor Bunnaman in the mid-morning session on Saturday.

WORKING AROUND THE ABSENCE OF...

Nolan Patrick remains sidelined with an upper-body injury, on a week-to-week basis. Restricted free agent Travis Konecny remains without a contract. On Sunday, Vigneault said that, from a training camp coaching standpoint, he sees a differential between the two different types of absences.

"It's unfortunate. But at the same time, we're doing and he's doing.... all the meetings. He's doing extra on the ice with our skills coach. Hopefully, this UBI will leave and he'll be back with us," Vigneault said of Patrick.

"He's here to do all the meetings, see the video we're showing. He knows all the drills we're going. He is behind, but he is not as far behind as someone that's not physically here at this time."

Either which way, Vigneault said on Day 1, the coach has to focus on the players who are available to play and work around the ones who are not.