I think everyone driving in F1 is pretty concistent. Only some are consistently to slow and to bad...Sainz can lap very consistent. So they can develop your car much better. Impossible if a driver does laps that vary so much you never know if it was the setup or driver.
When I look at the statistics at f1fanatics.co.uk Palmer ain’t that bad, only to slow compared to Hulkenberg and thus losing valuable points for Renault. And now the time has come for Sainz to put his money where his (big) mouth is. I sure do give him that, although I have my doubts if he is able to live up the expectations. Only time will tell.