It makes sense for the onside-kick alternative to be an untimed down, in order to prevent a team that takes a late lead from using the play to milk the last few seconds off the clock in lieu of transferring possession to the losing team for a last-ditch effort at a Stanford-band miracle. The untimed nature of the fourth-and-15 play also will help the losing team, if the losing team cuts the margin to one score late in a given game.
By making the play untimed, the losing team will have with an enhanced chance to win or tie. If, for example, a team is down by 10 points, scores a touchdown with two seconds left, and makes the extra point (also an untimed down), the team that is now losing by three can try to get the ball into field-goal range on the fourth-and-15 play, forcing a tie. If a teams kicker has the leg to connect from 57 yards, a 35-yard gain on the untimed down will give him the chance to do it, with no need to get out of bounds or spike the ball or rush the field-goal unit into position.
If the clock runs on the fourth-and-15 play, the only chance in that same circumstance would come from a 75-yard Hail Mary or a series of laterals aimed at popping someone free for a game-winning touchdown (if Gronk is playing deep safety).
That’s not an “unintended consequence,” per se. It enhances the goal of the rule: Giving a team that is losing late a reasonable opportunity to force overtime or win in regulation. In theory, a team can be down by as many as 16 points and still send a game to overtime if it scores a touchdown with one second left, makes the two-point conversion, converts the fourth-and-15 play by getting the ball in position for a reasonable shot at the end zone, gets there, and makes another two-point conversion.
All of this means that games won’t be truly over until they’re over, and that anyone who declare a game “over” and changes the channel could later be in for a rude (or welcome) surprise.
