It has taken nine months for David Moyes to assert his authority on Manchester United ’s under-performing squad, but the Scot finally displayed an iron fist with a public slap down of Robin van Persie at The Hawthorns .

On the ground where Sir Alex Ferguson waved farewell to management last May, Moyes took a huge stride towards settling into his predecessor’s shoes with an unmistakeable display of authority to his sulking Dutchman.

Van Persie, skating on thin ice having been booked and then warned by referee Jon Moss for reckless challenges, was clearly unhappy to be replaced by Danny Welbeck on the hour mark, shaking his head as he trudged off the pitch, but Moyes had no other option even if he later said he had planned before the match not to give Van Persie the full 90 minutes.

The fact that the 30-year-old had offered little during his time on the pitch to persuade Moyes to risk Van Persie’s temperament producing a red card was another indictment of the former Arsenal forward’s performance.

It was a big moment, one layered with significance, and how it plays out from here could define Moyes’s reign as United manager.

If Moyes is bold enough in the summer, he could do worse than consider making Van Persie the first sacrificial lamb of his turbulent reign as manager by selling the forward and delivering a clear statement of intent that the past has gone and the future will not centre around those who do not buy into the new reality.

Forget Van Persie’s disinterested performance here for a moment and consider the bigger picture and how the landscape appears for Moyes and United.

Statistically, Van Persie’s strike-rate for United since his £24m arrival from Arsenal in August 2012 – 44 goals in 71 appearances – is hugely impressive and the strongest possible evidence for those who would suggest that selling him would be madness.

He also injected charisma and belief into a team and club whose morale had been crushed by Manchester City’s 2011-12 title success.

But as Ferguson proved repeatedly by dispensing with the likes of Paul Ince, Mark Hughes, David Beckham, Roy Keane and Ruud van Nistelrooy, there comes a time when a change has to be made and, just 18 months into his United career, that moment may have arrived for Van Persie.

The similarities between Van Persie and Van Nistelrooy are striking and do not stop merely with their shared Dutch roots.

Van Persie’s arm-waving dissatisfaction with his team-mates was straight out of the Van Nistelrooy text book for a start.

Van Nistelrooy was even more prolific than Van Persie, scoring 150 goals in 219 appearances, but United became over-reliant on the striker and predictable in their approach.

With Van Persie, United suffer the same problem and his lack of pace and mobility make Moyes’s team pedestrian and lacking the variety required to break down even the most limited opponents.

His complaint in Athens last week following United’s defeat against Olympiakos, that team-mates were occupying his space and pretty much suffocating him, were telling in that they highlighted the frustrations that were evident on the pitch here in the Midlands.

But United’s performance against West Brom once Van Persie was sat on the substitutes’ bench was like a new awakening – with Welbeck offering the movement, pace and work-rate that his out-of-sorts team-mate had failed to produce.

With Wayne Rooney, Juan Mata and Adnan Januzaj lacking the blistering pace to make a difference from a deeper position, United really need a flying machine up-front to stretch opponents and open up greater options.

In this respect, Van Persie is more of a hindrance than a help and the glory days of last season appear like another lifetime.

But just like Van Nistelrooy, maybe Van Persie will ultimately prove to be a star than shines brightly, but briefly, at Old Trafford.

He delivered the title last season, significantly when Rooney’s mind was elsewhere and focused on a power struggle with Ferguson, but now that the England forward is back in form and favour, Van Persie’s star has waned.

So maybe it is time for Moyes to consider a new approach.

When Ferguson sold Van Nistelrooy in the summer of 2006, he had two young wannabes by the names of Rooney and Ronaldo straining at the leash, desperate to take centre stage.

Welbeck and Januzaj are not in the same class as those two, but if Moyes can find the right striker this summer, losing Van Persie may not be quite so unthinkable.

For now, however, Moyes must decide whether Van Persie should start against Liverpool next Sunday or if the new dawn is already beginning to eclipse him.