Ben McAdoo, the son of a western Pennsylvania coal miner and now the head coach of the surging New York Giants, launched his coaching career two decades ago by joining the staff as an assistant at Homer-Center high school, where he had graduated only a year earlier.

McAdoo had been a defensive tackle for the Homer-Center Wildcats, but he knew he was too small to be a star, even at the Indiana University of Pennsylvania, where he was a student. But he did know he wanted to be a coach, so he dived in at the ripe old age of 19.

In the 20 football seasons between the time he coached at Homer-Center and when he was named last January to replace the illustrious Tom Coughlin as the Giants’ head coach, McAdoo held 10 different jobs with nine teams, including the Green Bay Packers.

McAdoo is only 39, but he has been around the block. So when his star receiver, Odell Beckham Jr, flew to Miami after a game Sunday to spend an off-day Monday on a boat with three team-mates and Justin Bieber, McAdoo did not seem so concerned.

What he is concerned about is what his players do at work. And it is succeeding.

On a conference call with reporters on Monday, McAdoo said: “Players are off until tomorrow morning. We will see them tomorrow morning and they’ll get their workout in, and we’ll get ready for Green Bay.”

Yes, the Giants, winners of nine of their last 11 games, are to tangle with the Packers in a first-round playoff game on Sunday in Wisconsin, which will probably be a little colder than Miami. The Giants lost a regular-season game on 9 October at Green Bay, 23-16.

That loss sank the Giants’ record to 2-3, but they have rebounded under McAdoo. Their finest moment came when they snapped the Dallas Cowboys’ 11-game winning streak on 11 December by defeating them for the second time this season, but the Giants prevented Washington from making the playoffs by posting a 19-10 road victory Sunday in a “meaningless” game for them.

The Giants finished with an 11-5 record and made the playoffs for the first time since the 2011 season, which ended with the Giants toppling New England in Super Bowl XLVI. It was the Giants’ second Super Bowl victory under the fusty Coughlin, who retired after last season.

Because it is so hard to imagine any Giants player skipping off to Miami on a lark under Coughlin, McAdoo appeared to be lenient in comparison – even a pushover, especially as a rookie head coach. To wander off six days before a playoff game is not standard procedure.

The flip side, of course, is that he trusts his players and the process, and they have responded to him.

Giants linebacker Jonathan Casillas said of the Miami trip (on which he was not invited): “It just sucks. Those guys get so much attention for negative things, and I don’t see nothing wrong with it. They didn’t break any rules.”

After falling to Washington on 20 November, the Packers have won their last six games. Green Bay is a five-point favorite Sunday, so the Giants are facing a formidable challenge. They have enough to worry about besides the possible ramifications of the Miami caper.

Giants quarterback Eli Manning, who turned 36 on Tuesday, even joked about it, saying of the photos of the Miami boat excursion: “I think as a team we kind of always pride ourselves on being well prepared, so when I saw some of the pictures I was a little disappointed, just because obviously they didn’t pack accordingly. They didn’t have any shirts obviously, all long pants, no shorts, no flip-flops or anything. So I am just disappointed on their packing and not being prepared for that situation.”

Pressed for a serious answer, Manning said: “I don’t really get into what guys do on their off days. It is their off-day, and they can do what they want.”

Asked if he had off-days like that, Manning replied: “I haven’t had many of those. But hey, it’s different. On my off-day I am always in here getting prepared, talking with the coaches a little bit about schemes and different things we can do. But that is kind of what a quarterback has to do. If guys want to get away for a day, I think they were a little low on their Vitamin D and went to get some sunshine to get the Vitamin D up to make sure that they are staying healthy for the cold weather in Green Bay.”

Manning answered four more questions about the Miami excursion; he said he figured he would be asked about it by reporters Tuesday after he’d found out about it.

He playfully discounted some memes that had been created of him joining his team-mates on the boat, saying: “No, I was telling people that I was the one who took the picture because they wouldn’t let me in with my shirt off, so they made me take it.”

Besides, McAdoo had not been so dismissive of Beckham’s flamboyant behavior earlier this season, because it already had hurt the team. After Beckham received a taunting penalty in a dismal loss to Minnesota on 3 October, McAdoo pointed out that the penalty killed a promising drive.

Two weeks later, the Giants ended a three-game losing streak by beating Baltimore at home, with Beckham accounting for 222 yards, but McAdoo did not appreciate how Beckham had pretended to propose to a kicking net on the sideline. Beckham hit the net in a 25 September loss to Washington in frustration – and the net appeared to hit him back.

McAdoo said he had told Beckham to focus on the game – to not be a “distraction.”

It would seem as if the trip to Miami would be more of Beckham being the same – except, in McAdoo’s eyes, it wasn’t. It came on time off. When the Giants reported for a workout Tuesday, Beckham and his three team-mates were there.

“I handle my business,” Beckham told ESPN. “I’m a grown man. I do what I am supposed to be doing. I’m in the building when I’m supposed to be in the building. I don’t miss team meetings, none of that.”

Maybe he is not as much of a glum stickler as his predecessor, but McAdoo has his rules and enforces them in his way. Late Sunday afternoon, we will see if he can move the Giants deeper into January.