It was an unsuccessful gamble and the wrong player was subbed.
For a few minutes it looked as though BKDs presence, if not his contribution might make a difference but taking off Muamba instead of Eagles who was having a shocker handed the midfield and ultimately the game to Norwich.
I question whether going for the win when an away draw was on the cards was advisable anyway. Norwich were forced to make two subs without changing anything. If OC had kept his nerve, Lambert may well have taken the gamble and thrown on another attacker first which could have played into our hands.
We didn't offer much going forward up until the substitutions but that was largely due to the wastefulness of Eagles and the fact that the players seemed incapable of putting in the extra yards to join the attack after their outstanding effort against Arsenal.
There was no doubt we needed fresh legs, but Eagles should have been the one sacrificed. I don't have an issue with BKD coming on if we'd stuck with 451 but BKDs instincts drag him up top making a 442 which doesn't work for us. We know BKD can play in midfield/tackle back etc and if he'd stuck to the task it might have come off, but he piled forward and Ngog became superfluous.
Alternatively he could have subbed both Eagles and Ngog with BKD playing up top and someone else working the wing but he didn't, the midfield was surrendered and we paid the price.