The fact Kakashi no doubt tried his best doesn't make him an excellent teacher. It made him a respectable teacher, but even a totally average and adequate teacher can be respectable as long as he gives all he has got to the teaching.

Kakashi pushed Naruto to somebody like Ebisu, who is a total loser and a fool. This is the man who failed miserably to teach and handle Konohamaru. An idiot like Naruto gave Konohamaru more valuable lessons than Ebisu. This reveals one thing: When things got serious, Kakashi abandoned Naruto and concentrated on saving and helping Sasuke. This is pretty natural considering how similar they are, like has been said many times in the previous posts.

However, this fits Kakashi's character perfectly as well as the nature of the series (well, before the fillers started, anyway). It doesn't make him an excellent teacher but it does make him a stern and succesful ninja. Happenings like this are what make Naruto the series it is.