A moment of ruthless decision making from Barry Ferguson turned his Rangers dugout debut from a disaster into a dream at Rugby Park. The former Ibrox captain watched on horrified as Kilmarnock bullied his team into a 2-0 lead that could have been more. Young Clinton Nsiala was badly at fault during Philippe Clement's final game in charge against St Mirren, and was to blame for Killie's second after a soft header and weak attempted challenge on Brad Lyons, who curled a fine strike past Jack Butland. Ferguson had seen enough and hooked the young Frenchman after less than half an hour, bringing on Ridvan Yilmaz to play right back and moving skipper James Tavernier to centre back. It had the desired affect, with Yilmaz starting the move that saw Vaclav Cerny pull one back before half-time. But the analysis at the break was unforgiving, especially on Nsiala, as Kris Boyd got stuck in on Sky Sports. He said: "Look at this from Nsiala. Maybe he can get away with the first one but then he just dips his two in for the second one. The header is poor but then that...a centre back challenging like that? Wow. Let's be honest, it was Nsiala that came off but Barry Ferguson cold have taken any of Rangers' outfield players off in that first 30 minutes. They were absolutely woeful to start the game. "It could have been him or Propper because the two of them are being absolutely bullied by the two Kilmarnock strikers, even when the ball is going in the box. Corners, free-kicks, they've really, really struggled to deal with them." The second half was a different story, however. The visitors roared back with three unanswered goals - two from Cyriel Dessers and a clincher late one from Nedim Bajrami. And while the call to replace Nsiala earned Ferguson plenty of credit, there was an acknowledgement that it was a learning moment for the young defender rather than a point of no return. Boyd said: "You've got to give a lot of credit to Barry and his staff because it's not easy, especially when it's a young boy, to take him off and then all the focus shifts to him. As I said at half-time, it could have been any one of the outfield players that came off after 25 or 30 minutes. It was really poor and you felt it was going to be the same problem going forward, but after that, they regrouped and from then on, they totally dominated the game. "However the young boy will feel, Nsiala, sometimes you just need that in your career. You just need that moment. You look at a lot of the kids coming up through the academy and they're always told how good they are. Then they hit a level, it starts to go a little bit wrong and there's questions asked of them. They go into their shell and struggle to come out. "It might do him the world of good tonight. Rangers were able to to turn the game on its head and were comfortable winners. But I'm not sure that would have happened if he'd left Nsiala on. I really don't. Barry or the staff will either have him in the office tomorrow or on the training field, put an arm round him and explain the situation. Sometimes as a young kid, those setbacks can help you later in your career." James McFadden was impressed with Ferguson's bravery, adding: "Credit to Barry and his coaching team, they make a brave decision to make a change that early. And it worked for them. Barry Ferguson, Neil McCann and Billy Dodds were absolutely loving it at the end there. They've come into an extremely difficult situation, so it's quite right they lap it up. Rangers looked stronger as the game went on, they didn't wither." Meanwhile, former Gers midfielder Steven Davis is keen to see how Nsiala comes back from his night to forget: "It's never nice to be taken off that early in the game but he's going to have to react to it. Barry and the staff will get round him, explain the reasons why and hopefully moving forward as well. He's a young lad trying to learn the game and he's going to have set backs. It's about how you react to that and I'm sure the staff will look after him."