Why don't more running backs today carry the ball Tiki Barber-style - high and tight - to reduce the risk of fumbles?
In reference to this article.
This question originally appeared on Quora. 
Answer by William Petroff,
Most players don't have a fumbling problem.
The reality is that most players don't need to change how they hold the ball because there's nothing wrong with how they hold the ball. It's worth noting that Tiki Barber had an actual fumbling problem before he changed the style in which he held the ball. Over his first seven years (the pre-Coughlin era), Barber fumbled the ball about 2.7% of the time he touched it.[1] That's so far above what should be expected that it necessitated a change and so Barber, to his credit, made adjustments.
However, when looking at most running backs, you don't see anywhere near the same amount of need for change. Going back through the last three seasons and looking at players with at least 40 rushing attempts and 100 over-all touches in a season (of which there are 150 such samples), we can see the following:
- Only 19 players (about 12.5%) had a fumble percentage greater than or equal to 2%. Of those 19 players, 6 were either quarterbacks or players who were assigned a significant amount of return duties, while another 10 are currently back-up running backs.
- 76 players (about 50.5%) had a fumble percentage less than or equal to 1%.
- 36% fumbled at an equal or lower rate than what Tiki Barber accomplished over the last three years of his career (about .77%).
So there's not really an epidemic of "fumble-itis" going on in the NFL. And while there's no such thing has having a fumble percentage that is "too low," we have to take into account that how you hold the ball affects how you run with the ball. In the referenced article, Barber mentions how the change in grip changed how he ran:
My feet were close together, and I was more balanced. The unintended consequence of carrying the ball like that is that I became a more powerful runner.
While it certainly helped him, one of the primary reasons that it did is because it really just accentuated the style he was already suited for. Asking a running back like Reggie Bush to do the same thing, while it might make the rate at which he fumbles lower than it is, it also might impact on how he runs the with the ball in a negative fashion. If Bush has to run with his feet closer together and with his hands closer to his body, it might not allow him to do all of the spin moves or the quick shifts in direction that make him as elusive as he is.
So, since athletes and coaches tend to be risk-adverse, there tends to be a belief of not changing things that aren't really problems, even if the change could make things better.
[1] A "touch" here being rushing attempts plus receptions. It should also be noted that it's somewhat hard to develop a baseline for what league-average is in this context given the complexities of having to deal with quarterback fumbles in the pocket and quarterback fumbles on rushes but, when looking at non-quarterbacks with at least 40 rushing attempts, the average fumble percentage over the last three years has been about 1.2%.