שיר השירים פרק ב:ה
סַמְּכוּנִי בָּאֲשִׁישׁוֹת -- רַפְּדוּנִי בַּתַּפּוּחִים:
Fine wines improve with age, so to halachic authorities. Chazal refer to young rabbis as "tzurba d'rabanan", referring to their tendency to be rough around the edges. It takes time and experience to come to a proper conclusion. While halacha itself is pretty cut and dried for simple cases, any real case has a multitude of mitigating factors. For example, I have a friend who became a ba'alas tshuva in her 50s. She had a minor stroke and for a few years was unsteady on her feet, so she used a cane outside. She asked her rav if she could use the cane on shabbos to walk to shul. She told him that she didn't use it in the house, so she thought there was probably no heter. As they were discussing the issue, though, it turned out the reason she didn't use a cane at home was because she had installed railings! It was only because the rav had enough experience to ask the right questions given her age, level of observance, community, etc that a proper halachic conclusion could be reached. (She was able to use the cane to walk to shul on Shabbos while she needed it.)
The mark of a good apple, on the other hand, is its freshness. The purpose of agada is to draw ones heart and emotions to avodas HaShem. Every generation needs to be approached in a way that "sings" to him. Agada (or drush) needs to be fresh and tailored to the generation.
An additional dimension that R' Auerbach expresses is that a wine jug loses its status as a vessel with even the tiniest hole. Other vessels retain their status even with much bigger holes. A vessel that holds groceries or laundry works just as well with a hole in it as without. A wine jug, on the other hand, has no value once it has a hole of any size; letting air in ruins the wine. So to halacha, letting in outside (non-Torah) influences, does nothing but distort the whole halachic process.
No big mussar lesson here; I was just interested to see that even the most poetic medrashim have a precision I hadn't imagined.