On Saturday O'Neill also felt obliged to leave the rejuvenated but recently injured Tony Cottee on the bench at his former club. In attack he paired the reserve striker Graham Fenton with another Hammers fan, Muzzy Izzet, who must be wondering if he, too, needs a move to a bigger club to earn wider recognition for his work in midfield after being overlooked again by the England coach, Glenn Hoddle.
Thanks to West Ham's own defensive deficiencies as much as anything else, with Neil Ruddock suspended and Rio Ferdinand looking about as safe as newly condemned houses, the makeshift formula seemed to be working when Izzet fired Leicester into a 26th-minute lead after a neat build-up involving the three midfield men: Parker, Lennon and Ullathorne. But it proved merely an illusion and it was not until the last 10 minutes, with the game virtually lost, that Leicester became an attacking force once again.
It must be deeply frustrating for O'Neill to see his colleagues in the managerial game like Alex Ferguson leave strikers such as Teddy Sheringham and Ole Gunnar Solskjaer out of the Manchester United side, and even West Ham could afford the luxury of leaving John Hartson on the bench on Saturday. In his absence, Paul Kitson was a revelation, if only because it seems so long since he has played regularly that most have forgotten why Harry Redknapp bought him from Newcastle in the first place.
His first Premiership goal for almost 11 months, against the club where his career began, put the Hammers back on level terms and he and Ian Wright - prepared to drop deeper these days and provide passes such as the one that set up Kitson - have the makings of a good understanding.
Behind them Redknapp has assembled yet another new midfield unit, one that looks his best yet with the excellent Eyal Berkovic supported ably by the industry and sharp-shooting of Steve Lomas and Frank Lampard, whose deflected shots took West Ham into a 3-1 lead.
Trevor Sinclair and Marc Keller, signed from Karlsruhe in the summer, also contributed to an impressive second-half performance that was only spoiled in the closing stages by Lampard's unlucky own goal.
Goals: Izzet (28) 0-1; Kitson (37) 1-1; Lomas (56) 2-1; Lampard (76) 3-1; Lampard og (87) 3-2.
West Ham United (3-5-2): Hislop; Pearce, Ferdinand, Dicks; Sinclair, Lomas, Berkovic, Lampard, Keller; Wright, Kitson (Moncur, 90). Substitutes not used: Breacker, Potts, Hartson, Sealey (gk).
Leicester City (5-3-2): Keller; Savage, Sinclair, Elliott, Walsh, Guppy; Lennon, Ullathorne, Parker (Campbell, 61); Izzet (Cottee, 66), Fenton (Wilson, 71). Substitutes not used: Oakes, Arphexad (gk).
Referee: S Lodge (Barnsley).
Bookings: West Ham: Wright. Leicester: Savage.
Man of the match: Lomas.