After falling to the Edmonton Oilers on Tuesday night, the Philadelphia Flyers' losing streak reached five games. The Flyers' run of poor play has come despite a relatively manageable schedule - four matchups against teams (Buffalo, New Jersey, Edmonton) that missed the playoffs in 2014-15, and one against a middling even strength team that barely squeaked into the postseason last year (Vancouver).

Earlier this week, we presented reasons for the team's decline in play. Poor special teams results and defensive zone struggles were major contributing factors to the three losses last week, in addition to injuries suffered by Sean Couturier and Pierre-Edouard Bellemare.

Those problems remain. The Flyers have yet to score a power play goal this week, and their penalty kill was blitzed to the tune of twelve high-quality scoring chances Tuesday in Edmonton. Also, their defensive zone turnover percentages this week (13.65% against Vancouver, 15.58% versus Edmonton) were both above the team's season average.

But since the Flyers left the confines of the Wells Fargo Center, things have seemingly gotten even worse. The losing streak began with an overtime loss to Buffalo and a Devils defeat that was tied entering the third period - two games that could have easily swung the other way. Their last three losses, on the other hand, were far more convincing. They were outshot in Buffalo and Vancouver despite trailing throughout in both games, and then had their worst puck possession game of the season against the Oilers. Only four goals in those three games certainly didn't help, either.

A new problem has emerged for the Flyers in addition to the existing issues. Forget about goals - Philadelphia is struggling to even push the puck into the offensive zone.

Failing at offensive zone entries

In order to score a goal, a team must attempt to shoot the puck. This has been the underlying assumption of all "puck-possession" metrics like Corsi and Fenwick that attempt to measure performance by counting shots.

But in order to attempt a shot, it helps to move the puck into the offensive zone. Over the past three games, the Flyers are failing to enter the offensive zone at their highest rates of the season.

First, let's define what a "failed entry" is. It could be an offsides play at the blue line or an icing due to miscommunication between defensemen and forwards. It could be a carry-in attempt that is knocked away by an opposing defender just as the puck carrier is entering the offensive zone. Finally, it could be a dump-in attempt that is quickly blocked and retrieved by the defense before the puck can be pushed deep.

The one issue that has linked the Flyers' last three road losses is an inability to successfully enter their opponents' zone.

Over the last three games, the Flyers' failed entry rate has exceeded 20 percent, meaning that more than one out of every five attempts at entering the offensive zone has been unsuccessful. It's a sizable jump from the previous two weeks, when the team hovered between 10% and 15%.

Philadelphia did struggle a bit in terms of zone entries at the start of the season (though not to this degree). However, that was understandable. The Flyers were not only adjusting to the start of regular season hockey, they were also learning a new system under a new coach, making the occasional miscommunication unsurprising.

In addition, their opponents in the early season were having similar issues, blunting the effect of the Flyers' failed entries. By now, other teams have settled in and are making smarter decisions with the puck in the neutral zone. The Flyers, on the other hand, have regressed.

Losing the neutral zone

A main reason for Philadelphia's strong performances against top competition early in the season was their play in the neutral zone. From the start of training camp, new coach Dave Hakstol preached the importance of aggressiveness in the middle of the ice, and players like Evgeny Medvedev quickly embraced the system.

The adjustment in tactics resulted in the Flyers winning the neutral zone battle more often than not in the early season. In six out of their first nine games, Philadelphia generated more zone entries than their opponents at even strength.

The tactics did come at a cost. Philadelphia was primarily playing a dump-and-chase game, as those entries were easier to generate than controlled ones. But so long as the Flyers were generating more total entries than their opponents, the overall effect was a net positive for the team. Hakstol's Flyers were almost using zone entries as a defensive tactic, keeping the pressure on opponents by forcing them to constantly retrieve loose pucks and spend less time generating offense.

But when the Flyers fail to enter the offensive zone at a high rate, Hakstol's entire gameplan falls apart. Now, opponents are sending play the other way once the Flyers are disrupted at the blue line, and are generating more entries than the Flyers. Combine that with the team's continued inability to enter the offensive zone with possession, and the result is shellackings at the hands of Vancouver and Edmonton.

It's no coincidence that the Flyers' Zone Entry For percentage dipped below 50% once the team began to struggle to enter the offensive zone. The problem has been at its worst on the west coast trip, as Philadelphia is both generating fewer zone entries than their opponents and struggling to enter the offensive zone with possession when they do successfully get in.

It's a recipe for long-term disaster.

One theory - line combinations

Philadelphia's struggles at entering the offensive zone are clearly a driving factor behind their poor play over the past three games. But that doesn't help to explain why the issues began in the first place, and whether they are fixable. The Flyers' failed entry rate skyrocketed starting with last Friday's loss to the Sabres. What could have changed over the past three games?

One potential explanation is the major line adjustments that occurred prior to the Buffalo game.

Frustrated after the team dropped two straight to the Sabres and Devils, Hakstol jumbled his lines and defensive pairings. Michael Raffl was moved to center, with Sam Gagner and R.J. Umberger on his wings, while Jake Voracek was dropped off the top line to play with Scott Laughton and Brayden Schenn. The pairing of Luke Schenn and Nick Schultz also made its first appearance.

Some of the line changes have not held. For example, Voracek was quickly returned to his spot on the top line for the following game. But new Read-Laughton-Simmonds and Gagner-Schenn-Lecavalier lines have taken the place of more productive past tandems.

At times, these combinations seem to lack anything in the way of chemistry. Via the eye test, it appears to have impacted the forwards' decisiveness through the neutral zone. In fact, the only line on Tuesday night to break even in terms of puck possession was the Giroux line - the sole group that had played together as a unit prior to last Friday's contest.

There isn't much in the way of data to support this theory. But intuitively, it does make sense. The Flyers' early season struggles in generating entries could be partially attributed to unfamiliarity with new line combinations, but once the players became more comfortable with their linemates, the failed entry percentages dropped accordingly.

Due to the wholesale line shifts, the forwards are essentially starting over, and their zone entries could be suffering for it.

Conclusion

There are a numbers of issues causing the Philadelphia Flyers' recent losing streak. Ineffective special teams and subpar defensive play are but two of the problems that the team has faced over the past two weeks.

But a new issue has arisen over the three most recent defeats. The Flyers are having serious trouble pushing the puck into the offensive zone, and they are losing the neutral zone as a result.

One reason for the struggles could be the wholesale changes in lines and defensive pairings. Some of these adjustments were necessary, due to injuries suffered by Sean Couturier, Pierre-Edouard Bellemare and most recently, Evgeny Medvedev. But other changes have been more questionable, including the elevation of Vincent Lecavalier onto a line with Brayden Schenn and Sam Gagner.

With the imminent return of Sean Couturier, it's possible that these problems will be short-lived. Or maybe with time, the new lines may start to function better as units. But in the here and now, Philadelphia's struggles entering the offensive zone are having a snowball effect on the production of the entire roster at even strength.

All statistics from War-On-Ice.com or manually tracked by Charlie O'Connor.