
Against Carolina, the Devils had a ton of problems with scoring and production outside of the best players on the team. And among the rest, there were too many rentals and guys at the end of short-term deals. Lack of permanence at the bottom of the roster was a real problem this year and in this playoff series.
In the 5 games against Carolina in the first round of the playoffs, the New Jersey Devils skated out 23 different players at some point, 24 if you want to also include Jakob Markstrom. Of those 23 skaters, 10 were defensemen and 13 were forwards. With the injuries to the blue line, it was a constant churning out of different pairings just to ice a full team without being shorthanded. And in some of those games, with the injuries, they were still shorthanded with fewer than 6 defensemen in the rotation. The only change in the forward group in those games was Daniel Sprong coming in for Tomas Tatar in one game, but otherwise, the forwards actually remained fairly healthy.
However, one of the problems with this roster, I think, that led to a deficiency against Carolina, and led to the lack of depth in the series that many have harped on since the game 5 defeat, is that so many of those 23 skaters were essentially mercenaries on one-year or short-term deals, or on the way out on the final year of a deal. Here is a chart of those who laced it up for NJ in the playoffs who are about to become free agents, according to PuckPedia:

So as you can see, of those 23 skaters who played in the playoffs, a full 8 of them are on expiring contracts, just over a third of the entire roster of players who skated in at least one game. That is a large number. And of those 8 skaters, only one is anything more than a rental or bottom of the roster plug-in, that being Luke Hughes. Luke is a core Devil and will get a long contract, so he does not fit in this discussion. However, he fit the bill of being on an expiring contract, so I threw him in. But for the purposes of this argument, he can be thrown out.
The other 7 are made up mostly of mercenaries. 4 of them were added late in the season. I wrote a half year with NJ in parentheses, as I did not want to calculate exactly what percentage of the season they played with the Devils, but in reality, none of those four guys played with NJ for more than 20 games or so, and so they were really with the team for a very short time. Those four- Cody Glass, Daniel Sprong, Brian Dumoulin, and Dennis Cholowski- were pure rentals. There is a chance Glass returns, as he is an RFA despite being 26 years old, but otherwise, these guys were all brought in for right now. There was no long-term connection with the team at all.
The others played with the team for the entire season, but it was mostly just for one season. The only exception that was not really a rental or mercenary is Nathan Bastian, who has been around for a while and is simply at the end of a “prove it” two-year deal, where he mostly just proved that he is a fourth-line player in the NHL. He has some good usage there, but that is about it. Tomas Tatar was with the team previously, but not last year, and was brought back on just a one-year, mercenary-type deal. And he wildly underperformed compared to how he used to play when he was here years ago, so that did not go well. Justin Dowling just finished a two-year deal, but barely played at all last season, so he almost felt like a rental when he was on the ice.
All in all, when you look at that list, Luke Hughes and maybe Nathan Bastian notwithstanding, that was a large and largely unhelpful group of short-term players for this team. The Devils struggled mightily with scoring and production outside of the top scorers on the team, and these players all played a part in that failure. It would be no surprise if, among that entire list, only Luke Hughes returns, and Tom Fitzgerald might have to go on a spree this offseason, bringing in players to fill out the bottom 6 on offense and the bottom pairing on defense. But this keeps the same problem alive: is he just going to keep bringing in mercenaries and short-term players at these positions, cycling them in and out, looking to find proper complements to the core of this team? Or is he actually going to sign some guys like these to longer deals, perhaps a few years in length, with the intention of building a longer-lasting team and a squad with more depth? His short-term moves for this season clearly did not work and were entirely unhelpful in generating offense in the playoffs. He will need to do better if he wants this team to go further next season. I would think he would need to find some more players for longer deals than just one season. Having that many players, and specifically that many rentals, on the team is not the answer.