Mari joined the Gunners on loan from Flamengo during the January transfer window. He has since made two starts for the north London club, helping Arsenal keep a pair of clean sheets in the process.
The Spaniard described how starting alongside 32-year-old Luiz has helped him, per Football.London's James Benge:
"He's had a good career and is a good football player, and also playing with him is so easy. These two games with him in the starting XI were nice because I only focused on my job and I didn't need to focus on other jobs.
"This is easy when you want to have a big game. We know he's an experienced player and sometimes when you need to do different things in the last minutes, like when you need to make calls or something like this, he can do it. For us, it's easy to play with him."
A proven track record of winning and some veteran savvy are among the best qualities Luiz offers a team. The decorated Brazil international is also technically proficient on the ball, able to build moves from the back with a range of passes to release runners between the lines.
Yet, for all his notable attributes, Luiz is often viewed as a mistake-prone liability. He can be guilty of costly lapses in judgement and reckless challenges.
He is at his best when he's partnered with a centre-back who offers a natural complement. Mari has proved up to the task thanks to his height, willingness to compete in the air and strength on the deck.
Those traits helped Arsenal earn a 2-0 win away to Portsmouth in the fifth round of the 2020 FA Cup. This was followed by a 1-0 victory over West Ham United in the Premier League, the last game before play was suspended until at least April 3 in response to the outbreak of the coronavirus:
Clean sheets had been a rarity for the Gunners this season, but things have improved defensively since Mikel Arteta took charge on December 26. Arsenal haven't conceded in seven games across all competitions on the former skipper's watch.
It's a possibility the 26-year-old would welcome, per Goal's Charles Watts: "I want to play a lot of years here with Arsenal. I am really happy now."
If Mari stays, he could partner William Saliba next season, once the 18-year-old has arrived from his season-long loan with Saint-Etienne. Alternatively, the experience of Luiz could still be needed to help underpin a back line undergoing a much-needed and long overdue transition.