It happens with every fan base. The Laker fans used to be merciless on Phil when he would not call timeouts and let the team "work through it". On and on, even with the best coaches.
Imo, however, we get mixed up between the two. Calling Pop a bad coach because he did not play Splitter and Duncan together enough is absolutely ridiculous. Stating that is not a wise move try this pairing without declaring Pop a horrible coach is I believe a legitimate complaint. Of course we can all question individual decisions, but on the whole, people who think Pop is truly a bad coach are basically divorced from reality, possibly psychotic. (Probably had great success coaching on the YMCA level; so of course its all so clear.)