The experience of UniCredit offers clues to what lies ahead.
In reducing the workforce by a fifth since becoming CEO in 2021, Orcel, a former UBS investment banker, slashed the size of UniCredit's central corporate teams, which he has described as "the bloated centre", including by shifting hundreds of employees into branches to boost the sales effort.
A process the bank calls "de-layering" has seen UniCredit cut the number of management tiers between the top ranks and client-facing roles from nine to four.
Helped by higher interest rates and strict cost controls, UniCredit has showered shareholders with cash from record profits, driving a 10-fold increase in its shares since Orcel's arrival, roughly three times the European sector's rise.
Yet executives say the hard-nosed discipline has created strain internally.
UniCredit said in July it had cut the costs of "non-business functions", except the digital division, by five times more than overall costs. Several sources said revenue-generating roles were valued more highly than support functions.
Banking supervisors monitor whether control functions including compliance and risk retain adequate staffing as banks pursue cost reductions.
A UniCredit spokesperson said Orcel's strategy had been a "continued search for operational excellence reshaping the organization, its processes and its people way of working" so as to "eliminate duplication and unnecessary privileges and reset the sector's efficiency frontier".
The cuts have never been generic or in pursuit of short-term goals, but always aimed at securing the bank's long-term future, the spokesperson said, adding that the alternative would be "an uninvestable institution".
Orcel will need a different skillset than the financial wizardry that helped him gain control of the German bank, Chicago Booth professor Kilian Huber said.
"The challenges he now faces are ... about managing culture and transition processes over many years," Huber said, predicting a "bit of a culture shock" at Commerzbank.
The takeover looks all but certain. The ECB has found no grounds to block it under a preliminary assessment, but highlighted a "challenging and long-lasting" integration process, made harder by cultural differences and tensions created by the hostile bid, Reuters reported this week.