Were two ways to win better than one?

Yesterday’s Washington Redskins game against the St. Louis Rams was a pretty dull affair. But in the dying minutes Redskins coach Jim Zorn made a fascinating decision.
Leading by two points with just under two minutes remaining, the Skins faced fourth down and half a yard to go on around the Rams two yard line. The Rams were out of time outs. Zorn had to decide whether the kick a field goal to put Washington up by five points or to try for the first down, thus denying the Rams the possession they needed to win the game, but leaving them in need only of a field goal if the fourth down effort failed.
Zorn opted to go for the first down. His team failed to get it, but the Redskins won the game when the Rams promptly went four and out.
Despite the positive outcome, Zorn’s decision is being widely criticized here in Washington. Respected sports columnist Thomas Boswell called it “as dubious a decision as you’ll see.”
But a moment’s reflection is enough to realize that Zorn’s approach was rational, and probably the correct one.
By going for the first down, Zorn gave his team two ways to win. They would prevail if the Skins got the first down and, failing that, they would prevail unless the Rams could march at least 65 yards or so and kick a field goal.
Had the Skins kicked the field goal, they would have won only if they prevented the Rams from marching approximately 70 yards (assuming a normal kick-off return) for a touchdown.
There’s no doubt that marching 70 yards for a touchdown with no time outs is more difficult than marching approximately the same distance for a field goal attempt with no time outs (at least once you advance the ball out of the shadow of the goals posts and get some operating room, which the Rams never did). And even taking into account the chance that a long field goal will be missed, Zorn’s defense was more likely to win the game for him with a lead of five points than with a lead of two.
But the cunning of Zorn’s approach was that he also gave his offense a very real chance to win the game. I don’t know all of the probabilities necessary to say for sure that, on balance, Zorn put his team in the best position to win the game by going for a very makeable first down, but I suspect he did. In any case, there’s no basis for claiming that his decision was highly “dubious.”