The Brackley based team had a very strong end to the recent pre-season period, but Schumacher said: "I see it more to do with the background.
"(To do) with the engineers, the infrastructure of the team itself. And I think these steps were taken some time ago," added the great German.
Although team boss Ross Brawn's future now appears very clouded, Schumacher is undoubtedly referring to the Briton's decisions to bring in the likes of technical boffins Bob Bell, Aldo Costa and Geoff Willis.
Former F1 driver Gerhard Berger agrees.
"I do not think those two (Lauda and Wolff) have been able to have any influence on the performance of the car," he told APA news agency.
"Why? Because this (2013) car predates their time. But we must not underestimate the impact of fresh wind."
Another pundit, the 1996 world champion Damon Hill, thinks Mercedes' boosted form is due to the team spending more time than usual last year designing the 2013 car.
"I think Ross Brawn had decided 'Listen, this year is a write-off'," he told the Sun.
"By the looks of things they'd been focussing on 2013 (last year) and pretty much shelved 2012. They'd looked worse than they are," added Hill.