At the start of training camp, Flyers head coach John Tortorella was surprisingly open about the fact that 36-year old defenseman Marc Staal — who was signed to a one-year contract in the offseason — had already been told by Tortorella himself that he likely wouldn’t play in every single game during the upcoming season, so focused the Flyers were on developing their many young blueliners.

This wasn’t exactly what Tortorella had in mind as the reason for a Staal absence from his lineup, however.

Staal is expected to miss significant time with an upper-body injury that he suffered last night in the second period against the Edmonton Oilers, after crashing awkwardly into the boards due to a collision with Warren Foegele.

The Fourth Period’s Anthony DiMarco first reported on Friday morning that Staal was expected to miss 4-to-6 weeks with his injury, and a source confirmed to PHLY Sports that the reported timeline was indeed the initial read on how long Staal might be out of the Flyers’ lineup.

It’s not an insignificant absence. On the low-end, Staal would miss 12 games with the injury, and could miss up to 19 contests if he requires the full six weeks to recover. At the very least, Staal is expected to be out through mid-November, and very well might not be back until December.

In terms of on-ice value, the loss isn’t devastating for the Flyers. Staal’s value to the team was always going to be more as a mentor to the young blueline corps as opposed to being a dominant force in games. Those days are long past for Staal, even if he’s still physically capable of handling a significant workload and did appear to be settling in just before the injury, delivering a solid performance on Tuesday against Vancouver and providing a few good shifts against Connor McDavid in support of the top pair of Travis Sanheim and Cam York in the first half of Thursday’s game.

In any case, his minutes will need to be replaced. In those first three games, Staal ranked fourth on the blueline in ice time (18:17), behind Sanheim, York and Sean Walker. In other words, he was a top-four defenseman for the Flyers in terms of usage. Now, they need a new one.

The good news? There’s a candidate for that role who just might be back in the lineup as soon as Saturday: Rasmus Ristolainen.

My understanding over the past few days was that Ristolainen was likely to return to action at some point this week, and after he missed both Tuesday and Thursday, that left just one possible return date: Saturday in Dallas against the Stars. It’s not a lock that Ristolainen will be cleared by then, but he skated with his teammates all week in practice and expressed optimism to the media regarding his progress on Wednesday. Ristolainen, in a sense, could slide right in to “replace” Staal and regain the role as a nightly top-four blueliner that he earned himself last season with his surprisingly strong defensive campaign.

Of course, it’s not quite as simple as moving Ristolainen into Staal’s vacated spot on the second pair. He’s a righthanded defenseman, as is Sean Walker, who was Staal’s regular partner. Most likely, Tortorella won’t put two RHD together on the same pair, instead giving each of them a lefty partner to balance out. That said, even if Ristolainen plays on the “third” pair, expect him to finish most games ranking in the top-four among Philadelphia defensemen by minutes played. By juggling pairs throughout the game and distributing special teams time, it shouldn’t be too difficult to hand Ristolainen the vacated 18 minutes per night once granted to Staal.

But this talk of pairings and handedness ignores the most important question surrounding both Staal’s injury, and the defense corps at large: what does this all mean for two young prospects still on the NHL roster — Egor Zamula and Emil Andrae?

Ristolainen’s looming return was only going to make the existing roster logjam even more difficult to navigate. Walker has played himself into a well-earned every-night role thus far. Ristolainen made legitimate improvements to his game last year, so he’s not someone who deserves to be in a rotation — as long as he retains those gains. Staal, at least through three games, was being deployed as a top-four blueliner.

With both Sanheim and York rightfully lineup locks, that left just one spot available for three players: Nick Seeler, Zamula, and Andrae.

The return of Ristolainen to an otherwise-healthy blueline easily could have meant the end of Andrae’s time in Philadelphia, at least for now. Zamula would require waivers to be sent down (Andrae remains waiver-exempt) and has also outplayed Andrae by a significant margin thus far. An eight-man blueline with Ristolainen back and both of Staal and Walker as lineup locks would have made it very difficult to get Andrae the NHL games he would need to further his development.

Now, with the Staal injury, the Flyers can basically just keep doing what they’ve done for the first four games, just with Ristolainen replacing Staal as a nightly lineup lock. Zamula and Andrae can continue to trade off games, and while the logjam isn’t gone, it at least remains manageable. At least in Tortorella’s mind, Zamula hasn’t yet played himself into an every-night role — he was asked specifically that after practice on Wednesday and confirmed that Zamula would remain in a rotation for now.

If anything were to change, it would most likely be the addition of Seeler to the nightly rotation, given the fact that he’s averaged just 13:59 minutes per night through four games. But for now, the status quo remains the same.

So to recap: Staal is out for a while. Ristolainen is close to a return. Zamula and Andrae remain in a two-man rotation for now. And the Flyers blueline corps rolls on.