Toro Rosso team principal Franz Tost says any underperformance in 2019 was down to their failings on the car's chassis, rather than issues brought forward by their Honda power units. Toro Rosso dropped two places in the constructors' standings from 2017 to 2018, dropping 20 points in the process.
Tost's claims come with pointed context, with Red Bull's senior squad also taking on Honda power next season, having been impressed by a series of early-season results from Toro Rosso, which saw Pierre Gasly finish fourth in Bahrain and seventh in Monaco.
Gasly also finished sixth in Hungary, after Red Bull had confirmed its switch to the Japanese marque, while the Frenchman will also step up from Toro Rosso next year.
Although they finished second from bottom in the standings, Toro Rosso arguably exceeded pre-season expectations after Honda's miserable run with McLaren, although Tost says things could have gone even better if they had a better grip on aerodynamics.
"I said last year quite clearly that it will not be an easy season, because of technical topics, which we have to sort out, but in the end, I must say that the power unit from Honda showed a much better performance than the chassis of Toro Rosso," Tost told Autosport.
"That means our deficiencies were not on the power unit side so much, we had our own deficiencies on the car.
"This was limiting us more, let me say it this way. Not the power unit. The power unit was OK."