The Patriots are losing a key part of their 2019 defense.

According to a source, Kyle Van Noy is signing a four-year, $51-million deal with the Miami Dolphins. The news was first reported by the NFL Network. This reunites Van Noy with former Patriots linebacker coach/defensive play-caller Brian Flores.

Van Noy tweeted “MiamiDolphins” with emojis wearing sunglasses.

Van Noy, 28, is coming off the best season of his career. The outside linebacker finished the 2019 season first on the Patriots in quarterback hits (15), tied for first in forced fumbles and second in sacks (6.5) to go with 56 total tackles. He set career highs in sacks, quarterback hits and forced fumbles.

Van Noy resurrected his career in New England. A second-round pick by Detroit, the linebacker never lived up to his draft status with the Lions. That’s one reason why the Patriots acquired Van Noy for just a sixth-round pick back in 2016. That deal turned out to be one of Bill Belichick’s best trades in New England. By 2017, he was a mainstay in the defense, starting at linebacker.

Van Noy won two Super Bowl titles with the Patriots. In three years in Detroit, Van Noy made 16 tackles and one sack. In his first full season in Foxboro (2017), he finished with 73 tackles and 5.5 sacks. In 2018, he finished with 92 tackles and 3.5 sacks. That year, Van Noy was outstanding in Super Bowl LIII, finishing with four tackles, three quarterback hits and a sack to help the Patriots defeat the Los Angeles Rams. He had 10 tackles and two sacks in the AFC Championship Game that year as well.

Van Noy might not be the only Patriots linebacker to leave. Jamie Collins is also a free agent and has a contract offer from the New Orleans Saints, according to the website neworleans.football.

The Patriots currently have linebackers/edge rushers Dont’a Hightower, John Simon, Chase Winovich and Ja’Whaun Bentley under contract.