Celtic's unexpected semi-final defeat to St Mirren a week ago wasn't just a staggering jolt to a young team gleaming with hot prospects.
Their manager, not blameless himself, accused his players of performing like spoiled kids. But for one player in particular - arguably the jewel in the crown - it was a stark reminder that there is a long way to go before strolling into the heady heights of an elite English Premiership team.
Victor Wanyama was outstanding in a 4-0 demolition of Dundee Utd, with Sir Alex Ferguson among other interested parties in attendance - but since then it's been a troublesome period for the precocious Kenyan.
At Hampden in the cup, he was a pale imitation of the brutish ballwinner-cum-playmaker that piqued the interest of Europe's elite through monstrous performances against Spartak Moscow and Barcelona. Lennon's recent move to 4-3-3 hasn't helped, with Wanyama and his companion water-carriers on either side strangled by St Mirren's numerical midfield advantage.
It was five against three, with Lennon abandoning the system after only 13 minutes. By then St Mirren deservedly led thanks to their blistering start, with a second narrowly missed chance from Stephen McGinn prompting the abrupt change in formation.
Perhaps too much had been asked of Wanyama, whose dynamism and presence gives the sense of two players worth of effort. The initial pitting of three midfielders against five suggests Lennon has faith that that athleticism can make up such numerical shortfalls - but not on this occasion.
With the Kenyan FA claiming Celtic's star asset is on the brink of joining "one of the big two clubs in the world" it seems increasingly likely that the growing hype in this case is justified. He is the real deal.
Yet despite apparent interest, given comments last year by Sir Alex, Wanyama doesn't appear a natural fit for Manchester Utd. Just eight months ago he told the official Man Utd website: "I don’t think we’ve had a holding player since I’ve been here. We’ve never had a holding player.
“We tried to get Roy Keane to do that but he just couldn't do it. He had to play a way that was his own way of playing, so I’ve not had it for 25 years. Why should I think about it now?”
If Wanyama's C.V. boasts one thing, it's of being effective in just that position - a midfield anchor. Making his debut for Celtic at centre-back, his unique selling points quickly became clear - a potent mix of strength, ball-winning, aerial ability and dominating physique. Recently his passing game has developed, not unlike Alexander Song at Arsenal who went from no nonsense ball-winner to rangy playmaker, catching the interest of Barcelona in the process, where he now plies his trade.
Broadly speaking, teams across Europe have been opting out of selecting those deployed in such "Makelele" roles. Javier Mascherano was relegated into defence for Barcelona, Manchester Utd use the technically gifted Michael Carrick, as Arsenal do with Mikel Arteta. Juventus' deepest midfielder is Andrea Pirlo and German giants Borussia Dortmund and Bayern Munich prefer ball-playing options like Sven Bender and Javi Martinez respectively.
If the holding midfielder is disappearing across Europe, it isn't to say that Wanyama couldn't excel. His battering-ram performance against Barcelona will remind Ferguson and co. that in the ever changing landscape of football tactics, there's inevitably a place for brute force. Or, like those who see their position in midfield ebbing away, he may find himself at centre-back - like Song, Mascherano or Daniel De Rossi.
He may stay in Glasgow beyond even this summer, considering his contract expires in 2015, but like all of the up and coming starlets on Celtic's books, ultimately his aim is outwith Scotland. While Lawwell will focus on getting the right price, Lennon must now step up finding a capable replacement.