Belichick feels that the 38-year-old has shown an incredible level of excellence throughout his 17 years in the league, especially against his side.
"For a career it's an unbelievable amount of consistent production," Belichick told reporters. "He'd probably be waiting longer to pass that record if he hadn't gone against me so many times.
"He certainly threw a lot of them against defenses that I had. His durability, his longevity, his production and that's why it is what it is, why that record is what it is.
"[Brett] Favre did it for a long time and on a very consistent level and Peyton has done the same thing even a little more. It's a phenomenal accomplishment."
Manning broke the NFL records for passing touchdowns in a season and passing yardage in the 2013 campaign.