THE excellent addition is not a perfect fit. No Mess means a big mess in the Devil middle.

While Lou Lamoriello was installing fuel injection on his Devils yesterday, he failed to beef up the engine block. He will head into the playoffs

with low compression on a crucial cylinder, and all he can do now is keep pouring STP in, hoping it makes it through June. A major hole remains unfilled, and the Devils will be scrambling to plug where Mark Messier would have fit so well.

Bringing in Alexander Mogilny for Brendan Morrison and Denis Pederson can only help. The Devils have been starving for goals in their 3-7-2 slide, and the former 76 and 55 goal man can still fire rockets off his jets.

But the Devils only have a dozen games to decide where he plays, and with whom. That’s the mess. With the trade deadline gone, the Devils have Jason Arnott and Bobby Holik as their top two centers, very good, but not great, and Holik has been learning the ropes of checking duties for more than a month.

The third line likely will be centered by Sergei Nemchinov or rookie Scott Gomez, and that’s where the difficulty lies.

There are options aplenty, but none is ideal. If Robbie Ftorek decides to break up the Arnott line, chaos really ensues. If he leaves that No. 1 trio intact, he can use Gomez as his third center, except that he’s already tried that and not liked the defensive results one bit, and that would mean either Claude Lemieux or Mogilny would have to play left wing.

That isn’t perfect, but it may be Ftorek’s best choice, despite the fact that Gomez’s offensive production vanished in the middle.

He could move Mogilny or Lemieux up to the left side of Holik and Randy McKay, but the Devils didn’t get either for the checking line, and if Holik is going to center a scoring line, who’s going to be this year’s Bobby Carpenter?

A third line of Gomez, Nemchinov and Lemieux/Mogilny can not match up against lines like those of Eric Lindros or Mats Sundin. Making a checking line out of John Madden and two wingers cuts down the ice time of the top three lines, and that’s been one of the problems the past three playoffs.

No, Lamoriello’s target had to be a scoring center, and Messier was exactly the ticket. When it came time to decide yesterday, sitting six points out of a playoff berth was not impossible enough for Messier to ask out, and he wasn’t going to be the one to cry uncle. On this one, everybody loses — Messier, Vancouver and New Jersey.

Mogilny will be fun to watch, and by consolidating excess talent in an exceptional player, Lamoriello has performed one of this year’s duties.

But the prime piece of work remains undone, and there has to be a sense of failure about that. The Devils have a chance to be glorious failures again. The rest of the league has hope.