When a striker is removed from a forward line, there is a vacancy. When he is top scorer, target man, local hero and resident hell-raiser rolled into one, the void is vast.
When he is not replaced in the transfer market and when his existing understudy is promptly injured, the problems are compounded.
Manager Alan Pardew's credibility is undermined; he was parachuted in to the job by an unpopular owner, Mike Ashley, and his initial vow to keep Carroll seemed a populist pledge of independence then.
Now it appears a mistake that leaves him looking misguided. Initially impressive results meant Pardew's position ceased to be a talking point, but this has been a damaging week. While he and Carroll can dispute the circumstances of the transfer, Newcastle's focus now ought to switch to the consequences.
While Carroll is injured and could not have featured against Arsenal tonight anyway, Shola Ameobi sustained a fractured cheekbone in Wednesday's defeat at Fulham and may miss much of the rest of the season.
Newcastle did not just fail to score at Craven Cottage: they rarely threatened to.
Ameobi's absence leaves Pardew with just three recognised strikers and a marked shortage of pedigree. Nile Ranger has promise but has never scored a top-flight goal; Leon Best has three, all against a West Ham United side intent upon self-destruction; and it says something that Peter Lovenkrands is behind both in the queue.
Among those who might otherwise have offered support to an understaffed forward line, Hatem Ben Arfa, the sole January purchase, is sidelined; so, too, is the borrowed Stephen Ireland. Pardew has begun a search for an unattached attacker, but the rumour that it may lead him to Jeremie Aliadiere offers little solace.
None of that bodes well for the remainder of the season. Newcastle can cite a total of 36 goals that is bettered only by the top four sides. Break them down, however, and 25 are shared by Ameobi, Carroll and Kevin Nolan, the midfielder with the predatory sense of a striker and a particular beneficiary of the departed forward's knockdowns and powers of intimidation.
Briefly Carroll's landlord and more frequently his sidekick, Nolan has apologised to any Newcastle fans who were offended when he pronounced himself "delighted" about his friend's move to Merseyside.
On and off the field, life is getting harder for Nolan. The gamble that Newcastle are taking is that a fine first half of the campaign provides a surefire insurance policy and that the fee for the overpriced Carroll can compensate for any deterioration over the remaining four months.
As it is, they are in the top half of the table. Every Premier League place is worth £800,000 in prize money and, were Newcastle to drop five positions, it would cost £4m. That would still be swallowed up by the proceeds of Carroll's transfer.
His exit will backfire, however, should Newcastle slip much further. Eight places separate them from the relegation zone and it is the improbability of so many strugglers outperforming them, rather than the comparatively slender margin of the six-point gap to the bottom three, that offers consolation.
Wednesday's muted performance against Fulham brings less. The sight of Damien Duff, whose own goal relegated them in 2009, depriving them of further points was an untimely reminder of a previous end-of-season collapse.
That Pardew started January talking bullishly of bidding for Robbie Keane and David Beckham and ended it with a glorified Championship attack is a further indication that expectations can change on Tyneside.
While Arsenal arrive at St James' Park with Newcastle aiming for an improbable double over the title challengers, their November win provides little encouragement.
They triumphed 1-0 at the Emirates Stadium. But the scorer then, soaring above Lukasz Fabianski to head in was, inevitably, Carroll.
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