Jake Plummer
Many experts wrote Plummer off after he joined the Cardinals. They couldn’t understand why Arizona stuck with him for so long because he was extremely average across six seasons. The Cardinals only produced a winning record in his sophomore year as he failed to elevate the franchise (via Denver Broncos).

Finally, he joined the Broncos in 2003 where he exploded into life. They made three consecutive postseason appearances and Plummer earned a Pro Bowl selection. He enjoyed winning seasons every year and became a reliable quarterback. It was one of the most unexpected career revivals in modern NFL history.