It's simple. The reason why Rangers have come from seven points behind to lead the Clydesdale Bank Premier League is built on the solid fundamentals.
They do not lose too many goals: two in the nine games since they lost against Celtic on December 27. They also tend to score: 20 in the same nine games. They have become predictable in another sense. If Walter Smith believes a team will pose great difficulty, he will play a 4-1-4-1 system. He did this against Aberdeen at Pittodrie and Celtic at Parkhead. Goalless draws and criticism followed.
However, the results look more than satisfactory from the height of first place in the league.
Smith, though, employed his Plan A for attack on Saturday. There was no surprise in the line-up but there was one factor that may be Smith's almost guilty secret. The man who quietly accepts charges of caution has even more silently created a passing team.
The midfield four of Steven Davis, Barry Ferguson, Pedro Mendes and John Fleck form the most enterprising quartet at Ibrox since the days of plenty when Tugay could not command a starting place. The present incumbents are not perfect, of course.
Davis is uncomfortable in a wide position, Ferguson has still to make a dramatic impression since a return from a long-term injury, Fleck is a talent rather than a fully fledged first-team player and Mendes, casually brilliant on Saturday, has had his off-days.
But they epitomise Smith's attempt to complement graft with craft. They all made their contributions on Saturday. Fleck was the most inconspicuous of the four but his run and cross led to a corner that forced a goal.
This may not seem much, but it is everything. These little moments are what decide matches. Rangers, trailing to an excellent Jamie Hamill goal after an incisive Kilmarnock move, won the match in the space of minutes.
It's simple. Fleck wins a corner, Madjid Bougherra wins the back-post joust with Manuel Pascali. Kris Boyd volleys home.
It's simple. Mendes wins a 50-50 with Pascali, slides a pass through and Kenny Miller scores.
It's simple. Miller pounces on hesitancy by Frazer Wright and shoots beyond Alan Combe. An encounter that had threatened to be a problem had become simply comfortable.
The midfield, harried and pressed by a willing Kilmarnock, had played their part but so had the rest of the Rangers team. Boyd had one of those afternoons that perversely provides ammunition for both admirers and detractors. He loses interest as quickly as a eunuch at a lap-dancing club. But he scored the goal that quietened nerves on the park and in the stands.
Miller, in contrast, ran about as if he was paid by the step. He has limitations as a footballer but effort is not among them. He took his goals well.They were always going to be enough for victory because Rangers are not leaking goals.
It's simple. Allan McGregor is back to his confident best. Kirk Broadfoot's one lapse was when he allowed a ball inside of him to reach Garry Hay. He was punished by the full-back's fine cross that Hamill converted. Both he and Sasa Papac were allowed to venture forward as the central defensive partnership of David Weir and Bougherra were untroubled by Kevin Kyle.
And this is where it becomes complicated. Rangers were bullied by Hearts and Dundee United in what threatened to be a winter of discontent in late November and early December. They were consistently dodgy at set-pieces with a particular susceptibility to the back-post header.
The Rangers personnel is largely the same but the failing has been removed. The chaos of defending badly has been replaced by the simplicity of defending well. This transformation requires hard work and, as ever in football, a degree of luck.
The rewards, though, are huge. They extend beyond a mere three points. Rangers are growing in confidence. They are unbeaten this year and the squad has become stronger. Fleck, who may be due a rest, has provided the odd spark. The supporters believe Aaron can do the same.
Bougherra suddenly looks both steady in defence and endearingly swashbuckling in attack.
There are also reinforcements. Steven Naismith, Maurice Edu and Kyle Lafferty were all on the bench on Saturday but are capable of making significant contributions.
There is no swagger about Rangers but one senses a quiet confidence. They are playing to a pattern, keeping it simple. No-one at Celtic, however, should doubt the difficulty that a fourth successive title chase now presents.
