The pre-season games were already in place when he arrived. By all accounts he has completely ran them into the ground in training and If he is still not happy with their fitness levels then good, keep whipping them into shape. We will get there, and in the mean time a 70% fit Koeman side is fitter than any Martinez side.
Why not see them in action before you jump the gun?
Our players could very well have been gassed in these last few matches after very difficult training sessions. If that's the case, then I'd say the ends justifies the means. In the greater scheme of things, I would rather lose the first 3 matches and have our guys at 100% than win all 3 and have them still at 70%.