Meanwhile, Chelsea were also learning that his replacement, Mason Mount, cannot always be the answer.
Because in their high wing-backed determination to get back into the game, Chelsea kept getting picked off by West Brom.
Callum Robinson has only ever scored five Premier League goals and all of them against Chelsea – Saturday’s two either side of a well-deserved goal for Mbaye Diagne.
MORE CHELSEA NEWS…
Chelsea: Tuchel has 3 players who need dropping after West Brom defeat
Thomas Tuchel could sell £29m Chelsea star who Frank Lampard liked
Chelsea could sign four players after shock West Brom defeat
Mount did pull one goal back to make it 4-2 for a while – a tap-in provided to him by the hopelessly out-of-sorts Timo Werner who chose to pass at close range rather than risk embarrassing himself further this week with a shot.
But the comeback never looked on as Chelsea continued to look sloppy and lethargic.
“Simply, we were not sharp enough in this,” Tuchel said. “We didn’t catch didn’t catch the momentum to be one man down, and to be closer, and to speak more, and to be a bit more aggressive, and to be a bit more tighter, and to play it more as a block, and to make it hard to create chances and to wait for your ball wins and to counter attack.