Ranking college football's 40 most impactful transfers over the past five years, from Joe Burrow to Caleb Williams

The transfer portal has gained popularity over the years and is now a resource for college football coaches to fill holes and revamp their rosters.

New coaches have used the portal to quickly turn around struggling programs. Established coaches have used it to fill holes quickly while high school prospects develop. Quarterbacks are taking advantage of the opportunity to change schools if they aren't the starter at their previous school.

Over the past five years, thousands of players have entered the portal and made an impact for their new teams. We have seen players go from FCS to Power 5, change teams within their conference and even go from backup quarterbacks looking for a shot to Heisman winners.

We looked at the past five years and picked the top 40 college football transfers who either made an impact or are expected to make an impact at their new destinations.