He could not have foreseen the injuries and Covid cases that took the wind out of Chelsea’s title challenge. But he did recognise the potential of the midfielder, who had already impressed at West Brom last season.
Gallagher was pencilled in to compete for a first-team place this term — and had he remained at Stamford Bridge there is every reason to believe he could have followed in the footsteps of Trevoh Chalobah by forcing his way into the picture.
If not for Patrick Vieira’s persistence — calling daily throughout the summer — Gallagher would have stayed.
It was the Palace manager’s determination to secure the 22-year-old — and his promise to make him an integral member of his team — that convinced Chelsea to let him go. Tuchel still had to okay it, but this was an example of the German’s appreciation of long-term benefit over short-term gain.
While Gallagher would have been a valuable option, particularly when N’Golo Kante and Mateo Kovacic were injured, it was accepted that playing week in, week out would be in the best interests of everyone. Not to mention the prospect of working under one of the Premier League’s greatest-ever midfielders.
Certainly, no one is complaining now — and Gallagher is seen as ready-made to return to Chelsea and compete with their stellar midfield.
England have also benefited, with the player now a serious consideration for Gareth Southgate’s World Cup squad in Qatar. That is testament to the progress he has made at Palace, with Tuchel particularly impressed with his energy levels, privately comparing them to Kante’s.
Gallagher has also passed his manager’s ultimate test for any player with ambitions of forcing their way into his plans.
Tuchel’s expectations are clear: he wants any loanee to not only improve the team they join but to be a standout performer.
Gallagher has met that remit, scoring seven goals and making 24 appearances for a team some thought would flirt with relegation.
It is a measure of his importance to Palace that Chelsea will be mightily relieved they do not have to face him on Saturday, due to Premier League rules over loan players, while Vieira is left with a sizeable hole to fill in his side.
The big question going forward is whether Gallagher will make that breakthrough in a Chelsea shirt?
That is always the doubt surrounding the club’s homegrown talent, but the stories of Mason Mount, Reece James, Callum Hudson-Odoi and Chalobah in recent years provide ample encouragement. So does the gap that will emerge in Tuchel’s midfield when Saul Niguez returns to Atletico Madrid in the summer.
Chelsea are looking at options in the transfer market, with England’s West Ham dynamo Declan Rice a long-term target and under active consideration within the club.
Monaco’s Aurelien Tchouameni could be a cheaper alternative to Rice and Chelsea scouts are watching him intently.
Tuchel acknowledges the need to strengthen in midfield, but the return of Gallagher, along with a new signing, would leave that department bloated.
There would be little point in bringing Gallagher back to sit him on the bench, especially in a World Cup year.
Tuchel also has other areas he needs to address, with as many as two centre-backs on his wish list, with Jules Kounde the main target.
He also wants cover at wing-back and there could be changes up front, depending on the futures of players like Christian Pulisic and Timo Werner.
Tuchel is willing to put his faith in youth, but to earn that faith the highest standards are demanded, which is why, for example, he is happy to pitch Hudson-Odoi against Kai Havertz and Werner for a regular starting berth, regardless of their transfer fees.
That is the challenge that lies ahead for Gallagher. He will be given a chance to compete with Kante and Jorginho — and will be expected to deliver.