If you are able to indeed secure a clerkship, then a lot of it will come down to luck.
The law clerk I was working with this past summer was a T2 graduate whose first year grades were below the median. That notwithstanding, he managed to write onto law review and was able to get a clerkship.
Because of the type of work that he was doing (very niche), a V100 firm ended up giving him an offer.
But again, this REALLY comes down to luck. The clerk basically told me that that he was definitely not the norm.