Kedoshim: Anachronism In Midrash

A section of Midrash Rabba on Kedoshim duscusses Orlah, the fruits of the first three years, as well as brit milah.

Now, Avraham was commanded to circumcise himself and the male members of his household. Bereishit 17:

י זֹאת בְּרִיתִי אֲשֶׁר תִּשְׁמְרוּ, בֵּינִי וּבֵינֵיכֶם, וּבֵין זַרְעֲךָ, אַחֲרֶיךָ: הִמּוֹל לָכֶם, כָּל-זָכָר.	10 This is My covenant, which ye shall keep, between Me and you and thy seed after thee: every male among you shall be circumcised.
יא וּנְמַלְתֶּם, אֵת בְּשַׂר עָרְלַתְכֶם; וְהָיָה לְאוֹת בְּרִית, בֵּינִי וּבֵינֵיכֶם.	11 And ye shall be circumcised in the flesh of your foreskin; and it shall be a token of a covenant betwixt Me and you.

While he is told to circumcise the flesh of his orlah, he is not told what the orlah {uncircumcised flesh} is. Indeed, we see other orlah referred to throughout Tanach. We have uncircumcised lips, uncircumcised hearts, and uncircumcised ears, besides that of "foreskin." (In fact, one might easily read these others as metaphorical - in that they are not heeding the word of God or are not good speakers. However, from a perspective of analyzing the text without knowing a prior definitions of orlah, we need some way of narrowing the field.)

Various suggestions are given, but one interesting one follows (from parasha 11:6)

רב הונא בר קפרא אמר ישב אברהם אבינו ודרש

נאמר ערלה באילן ונאמר ערלה באדם
מה ערלה שנא' באילן מקום שהוא עושה פירות
אף ערלה שנאמר באדם מקום שהוא עושה פירות

Rav Huna bar Kappara said: Our forefather Avraham sat an darshened
It states {the word} orlah by trees, and it states orlah by man.
Just as orlah stated by trees refers to the place where it produces fruit
So too the orlah stated by man refers to the place where it produces fruit {=offspring}

Rabbi Chanin bar Pazi jumps to attack this:

א"ר חנין בן פזי
וכי כבר היה אברהם אבינו יודע קלין וחמורין וגזירות שוות
אלא רמז רמזה לו (בראשית יז) ואתנה בריתי ביני וביניך וגו'
מקום שהוא פרה ורבה

Rabbi Chanin bar Pazi said:
And did our forefather Avraham already know kal vaChomer {deduction a minori} and gzerot shavot {deduction via parallel words)?!
Rather a hint was hinted to him: {Bereishit 17}

ב וְאֶתְּנָה בְרִיתִי, בֵּינִי וּבֵינֶךָ; וְאַרְבֶּה אוֹתְךָ, בִּמְאֹד מְאֹד.

2 And I will make My covenant between Me and thee, and will multiply thee exceedingly.'

The place from which he is fruitful and multiplies.

Thus, Rabbi Chanin bar Pazi felt that it was anachronistic to assume that Avraham Avinu knew, and used, the hermeneutical principles to derive new laws.

Elsewhere we see claims that Avraham kept all the laws of the Torah, as well as Rabbinic ordinances, though it is seems from one such source that Avraham did not see these sources inside but rather intuited naturally how to conduct himself. This also might be called anachronistic, but it is a well established midrashic perspective, whereas the assumption that he knew kal vaChomer and gzera shava may not be. Also to consider: if we say he intuits it, why would he need a source here (unless perhaps if you say direct commands are different - and he did not keep brit milah before this)?