It’s always a bit unfair to judge Alonso’s teammates as it was young Schumacher’s, whenever they were on not so good machines, as they both were trully class-of-the-field drivers. Remember Irvine’s performances on those early Ferrari days? Eddie Irvine was throughout his career a top midfielder, “as good as anybody else out there, except for Michael, and no one is as good as Michael” as he would have put it.
It’s unfair because Schumi and Alonso outperformed enormously his cars in those years. And they had preference by the team (meaning that maybe Irvine had to do tests for Michael and Piquet crash into walls).
Maybe those Piquet’s results are just what the car was capable. Maybe any other “established” driver wouldn’t do better. Remember Nelson Piquet Jr. only lost GP2 series to Hamilton (and took 4 wins)