Erickson seemed generally clueless to me. His drafts were underwhelming and his coaching was less than mediocre. I'm a bit more forgiving because he inherited a sinking team although you could argue that he exacerbated the situation.
Nolan new jack about offense and put little faith in offensive continuity. We went from WCO, to modified Coryell (IIRC) to the Hostler and then Martz in three years. Nolan however could attract FAs with the best of them. Till this day I thank him for his helicopter ride with Justin Smith.
As for Singletary, he just wasn't HC material in general. He rode a weak second half schedule into a permanent role. Seemed too intense and knew nothing about game-planning. However, he did bench Chilo, start Goldson (IIRC) and bring the best out of Vernon Davis. Davis looked like a bust before Singletary sent him off.
[ Edited by 9erfanAUS on Jun 12, 2012 at 7:40 AM ]