You might be thinking of
this guy. He wrote a
paper on going for it on 4th down. The money paragraph states
[ QUOTE ]
The results are striking. The analysis implies that teams should be quite aggressive. A team facing fourth and goal is better off on average trying for a touchdown as long as it is within 5 yards of the end zone. At midfield, being within 5 yards of a first down makes going for it on average desirable. Even on its 10-yard line -- 90 yards from a score -- a team within 3 yards of a first down is better off on average going for it. In practice, however, teams almost always kick on fourth down early in the game. The only significant exceptions occur in the "dead zone" around the opponent's 35-yard line, where a field-goal attempt is unlikely to succeed and a punt is likely to produce little yardage, and on plays where the team has one yard to go and is near the opponent's goal line. Even in those cases, however, teams are much more conservative than the recommendations of the dynamic-programming analysis.
[/ QUOTE ]
I haven't read the whole paper, so I can't say how close his model corresponds with reality.