I would like to argue that the football practice by ballcarriers of extending the football out to the end zone pylon is not worth it from a risk/benefit standpoint unless it is 3rd down or 4th down.
There is a high risk of the ball being fumbled out of bounds out the end zone, which would give possession to the defense at its own 20-yard line. This is especially likely if the ballcarrier is leaping or diving and/or does not really have firm possession of the ball in his hands, or there are defenders nearby who could knock the ball out of his grasp.
On 1st down or 2nd down, this simply is not worth the risk. On 3rd down, there is a more compelling case, since you might have to kick a field goal instead if you could not score that touchdown. On 4th down and needing a touchdown, there really is much less risk as a touchdown is needed.
What percentage of plays that include diving for the pylon, regardless of the down, result in a fumble out of the endzone and a turnover?
You go for the TD when ever the chance presents itself. Turnovers are low chance events. Personally I’d prefer it if the rules were changed to require establishing a presence in the end zone. Until the player or the ball is established in the end zone it is not a score. Touch a body part or the possessed ball down someplace inside the endzone. Breaking the plane does not grant a first down or out of bounds elsewhere on the field. Yes the ball is marked at the forward progress point when stepping out of bounds but if a players voluntarily gives up the first down in an attempt to gain more yardage, the down is lost if he is unsuccessful.
It would be foolish to reach for the pylon without a firm grip on the ball, but I don’t recall a case of a fumble in those circumstances and do recall numerous touchdowns from reaching for the pylon. You don’t reach for the pylon unless you are heading out of bounds already so a fumble will not likely result in the ball going into the endzone and if you’re not heading out of bounds the goal line on the ground will be closer than the pylon anyway.
Once the ball crosses the plane of the goal line, it’s a touchdown, and play is dead. So there’s no risk at all as long as you can break the plane. That makes it a much surer play in all respects.
Actually the real problem is that on a ball fumbled out of the endzone the defense gets possession without ever controlling or even touching the ball. If the ball stayed with the offense and placed where the runner lost the ball the OP would be moot.
Ceteris paribus, I would agree with the OP. But the fact is that officials almost invariably rule that the ball crossed the plane prior to the fumble in those circumstances. Of course, sometimes they don’t and it’s magical.