BOSTON, MA – APRIL 13: From left, New England Patriots owner Robert Kraft, New England Patriots President Jonathan Kraft, head coach Bill Belichick and quarterback Tom Brady hold Vince Lombardi trophies on the pitchers mound at Fenway Park on April 13, 2015 in Boston, Massachusetts. (Photo by Maddie Meyer/Getty Images)

Bill Belichick’s run as the head coach of the New England Patriots is over, and it’s probably down to one huge mistake: he thought Tom Brady was done.

According to ESPN, Belichick surmised that Brady’s time at the top was over as early as 2014, when presented team owner Robert Kraft with evidence from a study that showed how quarterbacks begin dipping in their mid-30s.

Brady won three more Super Bowls with the Pats after that, though he clashed with the head coach over his training program.

Belichick finally convinced Kraft to believe that Brady was no longer useful after New England crashed out of the playoffs in the Wild Card Round in 2019/20. He went into free agency, joined the Tampa Bay Buccaneers, and went on to win a seventh Super Bowl at the age of 43.

It was a bad look for Belichick and Kraft, especially as the Patriots have been nowhere near as good since Tom’s departure.

“Bill had told me he couldn’t play anymore,” ESPN quotes Kraft as having said privately, “and then he goes out and wins the F- ing Super Bowl.”

The QB played at a high level for two more years before retiring at the end of last season, aged 45.

As for Belichick, he’s now set to coach elsewhere after being handed his marching orders dressed up as a mutual parting of ways.