Mercedes engineering director Aldo Costa and performance director Mark Ellis will leave the defending Formula 1 constructors' champions.

Aldo Costa will still work for Mercedes in a consultancy role from 2019 as he seeks to spend more time with his family. Who can blame him for wanting to spend more time in beautiful Italy instead of rainy Britian? The Italian began his career as a stress engineer for Abarth in 1987, moving to Minardi a year later (where he became technical director, in 1989) before joining Ferrari as its head of design office in 1996. He rose to become Ferrari's technical director in 2007 and left for Mercedes in 2012, taking four constructors' titles with the Germans. 

Costa will now do as his mentor (Rory Byrne) before him, giving expertise to the team, but not being in active duty.

His replacement, John Owen, will lead the engineering group and report to technical director James Allison. Owen, who joined the team in 2007, is currently chief designer and has worked at Sauber, Honda and Brawn. 

Mark Ellis will retire from his performance director role as of the middle of next season. He played a major role in the success of Red Bull, spending six years in Milton Keynes before joining Mercedes in 2014. Before all this he worked at Prodrive, Williams Touring Car Engineering and BAR Honda.

Ellis replacement will be Loic Serra, who currently is the chief vehicle dynamicist for the Mercedes F1 team. 

Toto Wolff stated on the teams website: “This is a significant moment for our Team and a great opportunity. We have said many times that you cannot freeze a successful organisation; it is a dynamic structure and I am proud that we are able to hand the baton smoothly to the next generation of leaders inside the team." The Austrian continued: "We have been in discussion for many months with both Mark and Aldo about how best to implement this transition and to empower their successors. They could not be more different personalities but they have both respected that difference and their legacy with Mercedes will stand test of time."
"Since the early days of 2013, Aldo and I have shared many dinners in Oxford as fellow European exiles, as well as some amazing days in the car at the Mille Miglia last year. I have got to know not just an outstanding individual but also somebody who has taught me so much about Formula One and the humility it takes in order to be successful."
"With Mark, when we first met we could never have imagined the success we would achieve together. He has been a sparring partner in the truest sense of the word – and I will miss our ‘tough love’ discussions with their shared passion for our Team and driven by the ultimate will to win."
"Mark and Aldo have both helped to shape the timing and manner of these changes, and the Team’s future is very bright with John, Loic and our entire technical leadership working under James’ direction.”

To me this all feels like there is a bit of a meltdown going on at Mercedes. Ever since they lost their edge over Ferrari in 2018, they have been stuggling on multiple aspects. They have lost Lewis Hamilton races by bad race strategies/wrong calls, they had a double DNF because of a mechanical failure, which had not happend since 1955, and last but not least; their updates (body and engine) did not deliver what they promised...

Is this the influence of James Allison? Remember that outside of Britain they don't regard him as high as they do on the island. Will we see Mercedes fall down the latter in seasons to come? Only time will tell..