Rav Samson Rafael Hirsch often finds connections between similar words in the Torah. What is the connection between evil - רעה - and shepherd - רועה - (especially in the same verse Bereishis 37:2 - אֵלֶּה תֹּלְדוֹת יַעֲקֹב יוֹסֵף בֶּן־שְׁבַע־עֶשְׂרֵה שָׁנָה הָיָה רֹעֶה אֶת־אֶחָיו בַּצֹּאן וְהוּא נַעַר אֶת־בְּנֵי בִלְהָה וְאֶת־בְּנֵי זִלְפָּה נְשֵׁי אָבִיו וַיָּבֵא יוֹסֵף אֶת־דִּבָּתָם רָעָה אֶל־אֲבִיהֶם)?
Sometimes in לשון הקודש one שרש can have opposite meanings because it connotes either the positive or negative of the form. E.g. עזוב תעזוב can mean to assist or more commonly to desert but the connection between the two is the main idea that can alternate in meanings.
How does this work here? רע in גמטריא אתב"ש is זג which can either mean "skin" or "seed." Skin is superficial (כדאמרי אינשי "Beauty is only skin deep.") just like evil is. Evil appears to be here, but it will eventually fade and decay away and the magnificently holy internality -- the פנימיות -- of everything will shine through. On the other hand, skin protects us just like a shepherd protects his flock. This is, by the way, similar to the speech of יוסף, as his outward concern for his brothers was on some deeper level lacking (although I don't need to say that for us it would be a mitzvah...).
Similarly, seeds are usually discarded and inedible. They do have, however, tremendous potential, just like a shepherd brings out the best in his flock. The גמרא in מס' סנהדרין tells that when חז"ל shechted the יצר הרע for עבודה זרה and znus, נבואה and and even chickens laying eggs were affected. There's a dichotomy here.