Love him or loathe him, you cannot ignore him.
Sam Allardyce has spent much of his career having to defend his methods, lambasted by critics bemoaning the style of football his teams play, and railing against the influx of foreign coaches in British football and their supposed superior approaches to the game.
But the facts are plain and simple: Allardyce gets results.
The former Sunderland defender by his own admission took on the toughest challenge of his managerial career in October last year when he returned to Wearside having been handed a mission to drag the club out of yet another scrap for Premier League survival.
He said at the time: ''It's a big challenge. Even at this early stage of the season, it's clear that we are in trouble.''
Sunderland were languishing at the foot of the table, level on points with derby rivals Newcastle - who would eventually succumb and be relegated after a torrid season - when Allardyce walked through the door to do what he does best.
Slowly but surely - and by no means as quickly as he had hoped - the now 61-year-old turned to his tried and tested methods, first making his team difficult to beat and then harnessing the enduring potency of striker Jermain Defoe to ease the club over the finishing line with a game to spare.
However, Allardyce's success at the Stadium of Light should have come as no surprise to anyone.
A man who calls a spade a spade has prospered almost everywhere he has been since launching his managerial career in Ireland with Limerick back in 1991, and his spells at Blackpool, Notts County, Bolton, Blackburn, West Ham and Sunderland have brought varying degrees of success.
Only at Newcastle, where he was appointed by Freddy Shepherd in April 2007 and then discarded by new owner Mike Ashley within eight months, did his stock fall with the Toon Army less than impressed by both the football on offer and the results it brought, a theme which was reprised during his time at Upton Park.
Allardyce's philosophy is straightforward: if you do not concede goals, you do not need to score too many to win football matches, and he is no fan of the tiki-taka' possession game.
He said: ''All this tippy-tappy stuff - everybody keeps on going about the right way to play football - is all a load of b******s sometimes.''
However, the way in which he implements his beliefs is significantly more complex with his attention to detail, meticulous planning and reliance on sports science and psychology all key elements.
It is an approach Allardyce is desperate to test on the international stage, and one which could ruffle as many feathers off the pitch as it does on it.