By Frank Dalleres Mercedes Formula 1 boss Toto Wolff admits he is at a loss to explain his team’s miserable performance after they missed a chance to capitalise on a rare off day for Max Verstappen and Red Bull at the Australian Grand Prix. World champion Verstappen retired from a race for the first time in two years when his brakes failed on lap four, leaving Carlos Sainz to lead home Charles Leclerc in a Ferrari one-two just two weeks after the Spaniard had appendix surgery. Mercedes, meanwhile, were nowhere in Melbourne. Engine failure compounded a weekend to forget for Lewis Hamilton, who …