It is difficult to know without having seen many games they have played. Seems to me that they may be doing what Leigh RMI did for one season a few years back. The following season Leigh dropped straight back down the league and were involved in a relegation battle. I think that Histon may be where they are partly due to being something slightly different from most other teams at this level, and if this is the case, they may be worked out by opposition teams, and sink down the league as more teams play them twice, or next season when they have got even more used to how they play.
Another explanation may be that it is far easier to be successful if you don't try to play football, and just hoof the ball up the pitch at every opportunity. I thought that it was interesting to hear the torquay players saying that was how histon played!