After three weeks of play, the two youngsters have been treated savagely by opponents with scant respect for their considerable reputation. Manning, the first player selected in the annual collegiate draft, has been intercepted eight times as his Indianapolis Colts have slumped to three consecutive losses. Leaf at least enjoyed the taste of victory in his first two games for the San Diego Chargers, but on Sunday his shortcomings were ruthlessly exposed by the Kansas City Chiefs.
Manning's Colts were demolished by the New York Jets, 44-6. The pressure continues to be intense on a young man who was hailed as the saviour of a moribund franchise, but the youngster threw two more interceptions. "He can learn more from playing and making mistakes than by standing on the sidelines watching," his head coach, Jim Mora, said.
Ironically, the Jets' victory owed much to their quarterback, Vinny Testaverde, who in 1987 was also the first player drafted. "The hardest thing to do is to be put right in as a young quarterback," he said, sympathising with his young rival.
Learning is now on the agenda for Leaf. The Chargers' passer completed just one of his 15 pass attempts for four yards, giving up two interceptions and three fumbles, one of the most statistically inept performances ever. Leaf had the 'flu all week, only leaving his hospital bed on Thursday. He probably wishes he had stayed there.
A third rookie, Detroit's Charlie Batch, fared no better than his young contemporaries. Batch threw two interceptions and gave up a fumble as the Lions fell to a 29-6 defeat at the hands of the Minnesota Vikings.
It was left to the old hands to show them how to do it. John Elway opened the scoring for Denver against Oakland with a touchdown pass, but age may finally be catching up with the 38-year-old. For the second game in a row he started but failed to finish, limping off with a pulled hamstring. The Broncos managed without him, prevailing 34-17.
In Miami, Dan Marino guided the Dolphins to a 21-0 win over Pittsburgh Steelers,who were stymied by another weak effort from their young quarterback, Kordell Stewart.
The oldest of them all, Seattle's Warren Moon, continued to defy logic with another impressive performance as the Seahawks maintained their perfect start at the expense of the winless Washington Redskins. Moon, who is 42 this year, sealed a 24-14 win with a 21-yard touchdown pass to Mike Pritchard.
The Broncos, Dolphins and Seahawks have all won their three games to date, with quarterbacks whose combined age is 116. Clearly, when it comes to the fine art of passing there is no substitute for experience.