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15. C.J. Beathard (2017 to 2020)
C.J. Beathard lands lower on this list than Ken Dorsey only because of the loss column. Beathard also never established himself as more than a backup quarterback.
Beathard went 2-10 in his time with the 49ers. However, he had a good team around him, which actually had Super Bowl potential.
He was able to throw for 3,469 yards, 18 touchdowns and 13 interceptions during his time as a Niners' starting QB.
