FANS are not slow to let you know what they think of you these days.

Just ask Ian Black. If the mood inside Easter Road got just a little chilly on Tuesday night as the Rangers midfielder stood ready to make his Scotland debut then the temperature in the Emirates this weekend is likely to be at the other end of the scale.

Judging by the heat emitted as the phone-ins and internet forums went into meltdown Arsenal fans are not too chuffed about the impending sale of captain and erstwhile talisman Robin Van Persie to Manchester United. The usual stuff about a lack of morals or guts or ambition have all been trotted out as Gunners train their sights on the Dutch striker, Arsene Wenger or anyone else who might dare to put their head above the parapet.

The fact remains, though that £24m for a 29-year-old forward is, well, £24m. Wenger will also salve his own personal disappointment at losing the services of his club captain again – Cesc Fabregas decamped for Barcelona last summer – by staring into the new faces in his squad, such as Germany's Lukas Podolski and Spaniard Santi Cazorla. They are not yet as marketable to supporters as RVP, but they might be soon enough.

It is not just that he has gone, though. Fans had an inkling that might happen when Van Persie refused to sign a new contract, with just one year left on his existing deal. What really stings is that he is going to Them.

It hurts that their side have slugged it out with United for the league title in the past and have been left on the canvas. It is especially painful for the last two seasons Arsenal have only been on the undercard as United continue to contest the main prizes.

The needle has gone in recent campaigns, the enmity that once existed now faded into memory. Players also seen attuned to that sentiment; Gael Clichy and Samir Nasri both made their way to Manchester City – as did Emmanuel Adebayor – before Fabregas returned to Spain. They left frustrated at a lack of medals, intent on mining silverware elsewhere, at clubs that seemed to be shining that little bit brighter. Arsenal's ambitions drew duller with every departure.

Selling Van Persie to United is symbolic of that. The arrival of new players swelled confidence, but that has been punctured by the sight of another notable individual choosing to chase glory with their main rivals.

"It's never great to lose players of that quality but he only had a year contract so we do not have a choice," said Wenger, treating the move with a cold logic.

The move would never have happened in the golden years of Wenger's reign – the days of the feted Invincibles – but the Frenchman has been forced to submit to a certain truth; he can no longer compete in the transfer market with certain other English clubs. Arsenal are a big club. It is just that they are not big enough.

Van Persie will relish the challenge to establish himself in a side hell-bent on wresting the title back from their city rivals this season. His illustrious performances last term suggest that he will swagger into the starting XI – probably with a cute turn, a drop of the shoulder and a cheeky step-over first – but he will be jostling for position with his new team-mates rather than rubbing shoulders with them.

United's attacking options are similar in strength to that which they boasted in 1999. Van Persie has Wayne Rooney for company up front, while they are joined by forwards like Danny Welbeck and Javier Hernandez. Dimitar Berbatov is also still on the books.

That draws comparisons with the class of '99 from Sir Alex Ferguson. "In 1999 I had Dwight Yorke, Andy Cole, Teddy Sheringham and Ole Gunnar Solskjaer, the four best strikers in Europe," said Ferguson, who is likely to give Van Persie his debut against Everton on Monday should his registration be completed on time. "We are going towards that now."

And perhaps also emulating that side's trophy haul.