Negative Humility
The role of Yehoshua in the episode of the spies is somewhat enigmatic. It appears that he needed to maintain a low profile because of his close relationship with Moshe.
This is the reason we find that Kalev did most of the talking. The other spies knew where Yehoshua stood, but were not as sure about Kalev.
But we also found that perhaps Yehoshua possessed a little too much humility. There are those who believe that Yehoshua should have asserted himself much more than he did. This also explains why he was in need of a name change, to help him through this ordeal.
Humility is definitely a very positive trait. But there are times when the יצר הרע can play tricks on us. It convinces us to refrain from action in the name of humility, when the reality is that humility needs to be cast aside for the needs of the moment.
This was Yehoshua. He needed to put aside his humility, and fight for the greater good of עם ישראל. This, too, is a valuable lesson in Midot.