Twenty years apart, on opposite coasts and in opposing conferences, what the 49ers and Patriots accomplished set them apart as the benchmarks of sustained contemporary NFL success. To dive into a comparison of the dominance built by the two coaching Bills (Walsh and Belichick) and the three Hall of Fame quarterbacks who starred for their teams (Joe Montana and Steve Young in San Francisco, slam-dunk future enshrinee Tom Brady in New England), I talked with four Super Bowl-winning head coaches who all had at least some tie to the 49ers of the past, and later competed against the Patriots of the present day.

Mike Shanahan, Mike Holmgren, Tony Dungy and Brian Billick all shared their recollections and observations of these two Super Bowl-era dynasties, lending their perspective on how we should view the long reign of the 49ers and Patriots. Which run was more impressive is, unsurprisingly, in the eye of the beholder.

[embeddedad0]"Hey, it's hard to win a damn game in this league, so if you've done what the Patriots have done - and this is hard for me to say - you've just got to go, 'Wow, that's special,' " said Mike Holmgren, the former Green Bay and Seattle head coach who served as the 49ers quarterbacks coach under Walsh (1986-88) and offensive coordinator (1989-91) under Seifert. "I didn't think I'd ever see another dynasty like the 49ers, with the way the NFL is set up with the draft and free agency and so forth.

"To have a team being able to dominate the way they've dominated is remarkable. They've figured out a way, and kudos to them, to somehow master the part about maintaining their excellence in the era of free agency and the salary cap while losing players. That's amazing to me. Look, I'm not a big Patriots fan now, but you've got to hand it to them, and I do."

Shanahan took over for Holmgren as Seifert's offensive coordinator in 1992, when Holmgren left to become the Packers head coach. He competed against the dominant 49ers when he was a Denver assistant and the Oakland head coach in the '80s, and then earned his first Super Bowl ring when 1994 San Francisco routed the Chargers in the Super Bowl. Later, as the longtime Broncos head coach, he was rare opponent who had a measure of success against Belichick's New England club, even knocking the two-time defending Super Bowl champions out of the playoffs in the 2005 divisional round.

"Be it going against Bill Walsh or Bill Belichick, even when I was a coordinator, you just knew you were going against somebody special when you went against them," said Shanahan, who most recently competed against the Patriots as Washington's head coach from 2010-2013. "Those are fun things to study, how those teams sustained that success.

"When you can put together an organization as well run as Walsh or Belichick built, you have a chance to stay on top for a long time. It doesn't surprise me at all what San Francisco did and for how long, given the way it was run. That program gave me the opportunity to have success in Denver, because we tried to emulate what the 49ers did and how they did it. And then with a guy like Belichick who knows what he's doing on both sides of the football, you're going to succeed."

Dominating a division and the continuity factor

But of course the Patriots and 49ers didn't just succeed. They dominated. Especially in their respective divisions. New England's 14 division titles from 2001-2016 have been won by a mind-blowing average of 3.4 games per season, with San Francisco's 12 NFC West titles just a tick behind at 2.9. The 49ers posted seven seasons of 13 or more wins during their dynasty era, with the Patriots racking up five such seasons, including this year's 14-2 mark.

Even the two seasons New England didn't win the AFC East or make the playoffs (2002 and the Brady-less year of 2008), they tied the champion Jets and Dolphins for best record, and lost out on tiebreakers. San Francisco's biggest division deficit in any season was one game - excluding the strike-shortened season of 1982 - and that only happened twice in 16 years.