Charles Woodson was a defensive back who made huge defensive plays all year, and also multiple touchdowns returning kicks. And then Michigan decided to give him some offensive snaps and he had some highlight plays on offense.
Peyton was considered a bit of a disappointment, despite his obviously outstanding college career, just because of all the hype around him. He was 0-4 against quality Florida teams in his career. His junior and senior years, the Gator DC was a guy named Bob Stoops. The Vols did finally, his senior year, win their only SEC championship, but they lost to Nebraska 42-17 in the Orange Bowl. The Husker win was considered so dominating, that they ended up in a split national title with Michigan. Both Michigan and Nebraska were undefeated.
Perhaps the biggest factor in his second place finish his senior year, was a 21-17 junior year loss to Memphis who won only three other games. Ryan Leaf didn't sniff a Heisman. He had a very good senior year, but Michigan beat Washington State (Leaf's team) 21-16 in the Rose Bowl. Now the bowl games had nothing to do with Heisman voting. It was a two man race between Woodson and Manning.
But Woodson's spectacular and more than once game changing plays, had been considered the prime reason that Michigan was headed for a co championship. And Woodson played as long as Peyton did in the NFL, eventually. Michigan had experienced four consecutive four-loss seasons from 93 to 96. So in 1997 when they were suddenly undefeated and headed to the Rose Bowl, it was a positive factor for Woodson.
Again, not a factor in the Heisman voting, but Tennessee barely beat a good not great, Auburn 30-29 in the SEC title game. Peyton was not the dominant college quarterback he'd become in the NFL.
But he filled a role that has happened many times in college sports. Like Oscar Robertson (in basketball), Jack Mildren, Bill Bradley, Troy Aikman (combined with Marcus Dupree), and others, he was considered the can't miss elite recruit that got close to a national title but came up short. But the recruits in subsequent classes, who gravitated toward a school that had "that guy," won a national title after the elite guy had moved on. Mildren at OU and Bradley at Texas, saw the impact of their notoriety in recruiting bring back to back national championships. Texas in 1969-70 and OU in 1974-75.
Tennessee won the NC with an underrated quarterback, Tee Martin, a year after Peyton graduated. Martin, who is now the OC at USC, was the first African-American quarterback from the SEC to win a national title. So even after graduating, Manning's college career disappointment was added to in 1998, a year after he graduated. Some had blamed Phillip Fulmer for the Vols failure to win the NC during Peyton's time. But he won it the year after Peyton left.
Some did consider Ryan Leaf a better pro prospect. The Colts apparently gave some thought to taking Leaf, but apparently not for very long. Leaf had a little bit of Johnny Manziel in him. He liked to party as much as play quarterback. He was an NFL failure. Manning is known by everybody as the consummate pro in terms of preparation. But Leaf was about 1000 points behind Woodson in the Heisman voting.
Woodson (433) 1815
Manning (281) 1543
Leaf (70) 861
Randy Moss (17) 253 .... Ricky Williams was fifth.