A pulpit rabbi send the following out as his message for AV.
What Talmud is he looking at?
According to the Talmud the 2nd Temple was destroyed because we didn’t practice what we studied. We knew how to learn, but we didn’t know what its message meant for us on a practical level.
The Book of Doctrines and Opinions: 
לפי התלמוד במסכת נדרים (דף פא, א), אחת הסיבות לחורבן הארץ בגלות בבל היא “שלא ברכו בתורה תחילה”
You have a good homiletic sense to work backwards from “message meant for us on a practical level” to the Ran.
Don’t you read Nedarim as applying to the First Temple?
I would guess it can be בבה מציעא ל, ב:
“דאמר ר’ יוחנן לא חרבה ירושלים אלא על שדנו בה דין תורה אלא דיני דמגיזתא לדיינו אלא אימא שהעמידו דיניהם על דין תורה ולא עבדו לפנים משורת הדין”
Thus we learned the letter of the Law, but did not know how to add some common sense and Chesed to it, which in practicality is always essential.
Oops, my keen homiletic sense seems to have caused me to overlook that small point 😉 I wonder if the pulpit rabbi also did?
FWIW, I see that R. David Dov Levanon maintains that the passage in Nedarim refers to the Second Temple.