Anthony Barry has transformed Chelsea into one of the Premier League's leading set-piece specialists, and the west Londoners could soon be without the 'brains' behind much of their success.
The Blues' assistant coach, who was appointed as part of Frank Lampard's backroom team ahead of last season, could be finally set to leave Stamford Bridge despite Thomas Tuchel's best efforts in holding onto the 35-year-old tactician.
Barry could follow his former employer to Everton if Lampard is appointed as manager at Goodison Park, according to The Sun.
The former Paris Saint-Germain boss persuaded Barry to stay at Cobham after Lampard was sacked, fending off interest from Cardiff City, Aberdeen and Tranmere Rovers - all of whom vying for his services in a managerial role, as per the Times.
Tuchel has openly credited the former Wigan Athletic coach with being the brains behind his Chelsea's success from set-pieces, offensively and defensively.
This season, the West Londoners have scored ten goals from set-plays in the Premier League - more than any other club, bar Liverpool (12).
Chelsea has also enjoyed tremendous success defending dead-ball scenarios conceding the third-fewest number of goals than any other side in the top-flight.
Andreas Christensen scored his first Chelsea goal after 137 appearances from a meticulously planned set-piece, and Tuchel was quick to hail Barry after the game.
The Blues boss wrote in Chelsea's pre-match programme: "It is important for us that we have many different players performing and we have many different goalscorers this season.
"I said after the Malmo game last week that it is a good sign when Andreas starts to score - and I think our set-piece coach, Anthony Barry, can be very, very proud!
"It is important to be able to score in situations like this and it is good that we have several different people who can score.
"The guys who get the chances need to take them, and when the games keep arriving we need the goals to win them so we can progress in all the different competitions."
While many players, like Christensen, will likely suffer from Barry's potential exit, no player will more than Mason Mount, who has grown into a dead-ball specialist.
This season, the 23-year-old creative technician has already registered seven assists in the Premier League, and Chelsea relies on his deliveries from set-pieces.
Tuchel's side is one of the most fruit-bearing sides from set-pieces this season, utilising Mount's deliveries to overperforming in dead-ball scenarios by 3.2 xG - more than any side in the league, as per Data Viz.
By losing Barry, Chelsea not only loses their nouse in either box, but Tuchel could also lose a slice of the fuel that has transformed Mount into a £67.5m midfielder that statistically rubs shoulders with the world's best.
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