Ian Rapoport of NFL Network reported Mack is headed to the Falcons on a five-year contract, which is still being finalized. Rapoport reported "the first two years are fully guaranteed, with plenty in [the third year]."
Zach Klein of WSB in Atlanta confirmed the deal.
Mack's agent, Tim Younger, told Mary Kay Cabot of Cleveland.com on March 2 that it was merely a business move, and they were keeping all options open as free agency begins:
We view Alex's decision to void as procedural. It was built into his contract to afford him maximum flexibility. For the first time in his career, he will be experiencing true free agency. Although we anticipate interest from multiple teams, he was very impressed with Hue Jackson and returning to the Browns certainly remains on the table.
D. Orlando Ledbetter of the Atlanta Journal-Constitution previously estimated it could cost around $50 million to land Mack, who previously voided the remaining portion of his contract with the Browns.
Mack was in line to make $8 million in each of the final three seasons of his deal with the Browns, according to Spotrac. So he was looking for a deal that exceeds that total along with a fresh batch of guaranteed money.
The 30-year-old center was a first-round pick of the Browns in 2009. He started 101 games over the past seven seasons, including all 16 during the 2015 campaign. The end result was the third Pro Bowl selection of his career.
Khaled Elsayed of Pro Football Focus doesn't believe the interior lineman played at a top-tier level last season, though: "As he worked his way back from injury, he didn't look like the guy he was before getting hurt. A very average year, with him not generating a lot of movement in the run game and allowing too much pressure. He's played a lot better and not made the Pro Bowl."
Ultimately, Mack made the right decision to void his deal because there was a better chance to land a lucrative, long-term contract at this stage of his career than there would have been in 2019. The Falcons' immediate interest illustrates that.
The Browns will need to fill the void either through free agency or the draft. Ryan Kelly and Nick Martin are the top prospects at the position, and they could be available outside of Round 1.