When West Ham dispensed with the services of Sam Allardyce last summer they were warned by pundits and rival fans 'be careful what you wish for'.
Well the club dared to embark on a bit of blue sky thinking and haven't looked back since.
Bilic has worked wonders on his return to East London and taken the club onto a whole new level with the likes of star signing Dimitri Payet the envy of the Premier League.
Lifting the FA Cup for the first time in 36 years is very much a possibility in what is the club's last ever season at their beloved Boleyn Ground.
Indeed had Bilic not been shorn of seven key first team players all at the same time over the winter - a spell where the Hammers drew six out of eight games - they could well be up where Tottenham find themselves now, on the cusp of a shock title bid in this most open of Premier League seasons.
Spurs dampening Hammers spirits
But the usual euphoria which would surround what promises to be the best season the club has enjoyed for decades is dampened somewhat by their North London nemesis.
Yes Millwall will always be West Ham United's true rivals.
But over the years the rivalry between the Hammers and Spurs has grown intense.
Many Spurs fans try to play down the rivalry and pretend they don't care a jot about West Ham, but they're not fooling anyone.
It is one of the major reasons Spurs fans are so relishing their own unforgettable season.
Seeing Tottenham riding high as London's top club and in with a shout of the Premier League title is enough to turn most West Ham fans green.
Spurs go marching on... and on...
Hammers are a knowledgeable bunch and will know Spurs deserve to be where they are too, even if they have been decidedly lucky on the injury front with key players Harry Kane and Christian Eriksen more or less ever presents.
Nothing would make the season sweeter for West Ham than putting the brakes on Tottenham's title charge at Upton Park, just like they put paid to their Champions League hopes on that fateful day back in May 2006.
Equally all but ending West Ham's outside chances of Champions League qualification would delight Spurs supporters and put the white icing on Mauricio Pochettino's cake this season.
It would be just West Ham's luck they could win their first major trophy for nearly four decades and be eclipsed by their bitter rivals' shock title triumph.
Hammers fans dare not contemplate it.