One day after a mutual parting with the most decorated NFL head coach in history, the New England Patriots hired the man to succeed Bill Belichick. Jerod Mayo is set to become the 15th head coach in franchise history, according to league sources briefed on the matter who were not authorized to discuss it publicly.

An introductory press conference to formalize the move is expected for the middle of next week.

Mayo, 37, will become the NFL’s youngest head coach. His ascension has been long planned. The team never reached out to a single other person for the role, including hot names like Jim Harbaugh, Mike Vrabel or even Ben Johnson, per league sources.

The Patriots wrote into his contract last January that Mayo would succeed Belichick as the next head coach. Because they did that and because they communicated that with the league, they were not required to conduct a full coaching search following the Rooney Rule.

Even when well-known candidates became available this week, Robert and Jonathan Kraft stuck with their plan. They’ve been confident for over a year that Mayo will make a good head coach, and they didn’t deviate from that plan this week.

In March, Robert Kraft said that Mayo had “no ceiling” on his ability to coach. He called him an “heir apparent.”

Now the Patriots are just finalizing what they’ve long planned.

Why were the Patriots not required to interview anyone?

The Patriots were able to hire Mayo so quickly because of language in Mayo’s contract that was unknown before Thursday evening and because of stipulations in the league’s anti-tampering policy and Rooney Rule, which typically requires teams to conduct in-person interviews with at least two external minority candidates.

When the Patriots re-worked Mayo’s contract last year to entice Mayo to turn down head coaching interviews elsewhere, they established in writing that Mayo would be the successor to Belichick. They then communicated that with the NFL.

A condition in the Rooney Rule and anti-tampering policy allows teams to bypass the typical interview process if they establish in writing a succession plan and communicate that with the league before the start of the season. Three teams have made use of this provision before: the Baltimore Ravens in hiring general manager Eric DeCosta, the Indianapolis Colts in hiring former coach Jim Caldwell and the Seattle Seahawks with former coach Jim Mora Jr.

So the Patriots knew all along that they wanted Mayo to succeed Belichick. And they didn’t deviate from that plan even with big names like Harbaugh and Vrabel on the market. — Chad Graff, Patriots staff writer

Why do they like Mayo so much?

Simply put, everyone seems to gravitate toward Mayo. Mayo was drafted by Belichick with the No. 10 pick in 2008, then went on to be a team leader as a linebacker. He entered a locker room fresh off the team’s 2007 undefeated regular season that was filled with star players — and quickly earned their respect, becoming a captain his second season. When he was injured toward the end of his career, Mayo grew close with Steve Belichick, Bill’s son, and studied film with him.

He didn’t initially enter coaching after retiring as a player in 2015, opting to explore other interests including in business. But Belichick lured Mayo back because he was so impressed with Mayo as a player and thought Mayo had a calling to be a football coach. Now, it seems the 37-year-old is poised to succeed Belichick. — Graff