Frank Lampard increased the value of Chelsea's squad in certain areas, particularly through integrating academy stars, but the former manager may have accidentally harmed the club's defence.
Indeed, he was ready to offload Antonio Rudiger and had little interest in renewing Andreas Christensen's contract.
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Rudiger was certainly open to moving on in the summer of 2020, having been told by Lampard that he would be the fourth- or fifth-choice centre-back behind Christensen, Kurt Zouma, Fikayo Tomori and the newly arrived Thiago Silva.
Lampard was keen to offload him as quickly as possible too, as the Englishman was concerned that Rudiger, a famously fiery character, might become an unsettling influence behind the scenes if unable to secure a transfer.
However, while no move materialised, Rudiger kept his head down, despite only featuring in two of Chelsea's first 16 games of the 2020-21 campaign (even if a groin problem did play a part in his lack of involvement).
It was clear, though, that Rudiger was surplus to requirements, meaning he found himself at the centre of more transfer speculation as the winter window opened.
Lampard's dismissal on January 25 changed everything, though.
Tuchel immediately reintroduced Rudiger into the starting line-up as a left-sided central defender in a back three and the rest is history, with the 29-year-old going on to prove himself one of the team's best players.
"Some things I saw coming," Rudiger subsequently said of his struggles under Lampard. "But then I was not in the squad, I didn’t see that coming. But I took it on the chin.
“I was close [to leaving]. There were two teams [interested] and maybe the one I was considering [joining] was PSG, and then there was Mourinho [Tottenham manager at the time].
"I had a chat with Lampard but then I was back on the bench.”
However, nearly two years on, and Rudiger's imminent exit is being met with devastation rather than indifference.
Tuchel was desperate to hold on to one of the most influential figures in the Stamford Bridge dressing room and Chelsea were willing to make Rudiger the highest-paid defender in the club's history.
To make matters worse, Christensen is also heading for the exit door.
And, just like Rudiger, he, too, struggled for game time under Lampard, with flimsy defensive performances knocking his confidence and sending him into a downward spiral.
The Denmark international ended up on the fringes of the squad and even though his contract was expiring, Lampard rarely spoke to Christensen about his future in west London.
The Blues eventually offered Christensen a one-year extension in the summer of 2020 but without a pay rise included, even though he was one of the lowest-paid players at the club.
Christensen sat on the offer while trying to force his way into Lampard's plans but, to his frustration, remained a bit-part player.
Again, though, Tuchel's arrival proved transformative, playing a key role in rebuilding his confidence and helping him improve as a player.
Indeed, Christensen is now close to realising the potential that he showed on loan at Borussia Monchengladbach and in his first season back at Stamford Bridge under Antonio Conte.
Sadly, despite both parties being willing to renew his contract, the talks collapsed over a breakdown in communication during the negotiations.
Bayern Munich and Barcelona both made their interest known, with Xavi Hernandez's new project at Camp Nou exciting the 25-year-old more.
The net result is that Chelsea are now set to lose two top-class centre-backs less than a year after allowing Tomori to move to Italy, where the former youth team star is now excelling at AC Milan.
Essentially, what should be an area of strength for the Blues is now a problem position going into the summer transfer window.
Of course, that is not just on Lampard, with an effective sporting director structure perhaps needed at Chelsea to avoid short-sighted thinking from under-pressure coaches.
The club will also forever remain grateful to Lampard for guiding them through the tough times which followed their transfer ban by welcoming so many academy graduates into the senior squad.
"I don’t think Frank did it to do them a favour," Tuchel said ahead of Saturday's Premier League trip to Everton. "I think every coach does it because it is all about helping the team.
"It is not about age. When you are ready, you are ready. I strongly believe you find your way if you have what it takes.
"So, I am very grateful for the quality the academy produces and grateful for the culture at Chelsea to push these boys through.
"It is our job to let them play and to prepare and push them on to this kind of level. This is what Chelsea is about."
Lampard understood that arguably better than anybody, and some of the moves he made led to the club's subsequent success under Tuchel.
However, it must also be acknowledged that he may have inadvertently played a small part in the exits of two key defenders.