What is "Dov Shakul b'Ish"?
Rashi: It is a bear that is Meshakel (kills) people. R. Yonah - this is like "v'Shikelah Eschem" (Vayikra 26:22). 1
So Rashi (Hoshe'a 13:8) explained Dov Shakul there. Radak there said that its children were killed. I think that he would explain similarly here; "b'Ish" means that it encounters a man. (PF)
Why is it better to encounter Dov Shakul than a Kesil with his folly?
Rashi: Kesilim entice him to veer from Hashem and His Torah.
R. Yonah: It is possible to evade damage from a bear, but not the damage of a Kesil and his anger.
Malbim: The bear damages the body; the Kesil endangers the Nefesh. A bear tears open the heart to extract the blood; a Kesil tears open the heart to enter Iveles and doubts. Sometimes man defeats a bear with a trap; one will not defeat a Kesil with his Iveles. A bear sometimes leaves (does not confront) man; a Kesil never abandons his Iveles.