Things have been tough (to say the least) over the past 20 years, but the Cleveland Browns have had some great signal-callers throughout their history.

Quarterback is the position that gets the most attention, and the Browns have at least been able to find quality talent under center.

Here are the five best quarterbacks in franchise history.

5. Bill Nelsen

Originally a 10th round pick of the Pittsburgh Steelers in 1963, he was a backup for his first two seasons before starting three injury-plagued campaigns. Nelsen was traded to Cleveland in 1968 and played well for the Browns for a time. He spent five years with the team, starting 51 games. He went 34-16-1, throwing for 9,725 yards, 71 touchdowns, and 71 interceptions.

Nelsen led Cleveland to three playoff appearances and made the Pro Bowl in 1969, as he threw for 2,743 yards and 23 touchdowns. Nelsen could end up being passed up by current QB Baker Mayfield, but as Mayfield has just under two seasons of experience, Nelsen holds his spot in the top five.

4. Bernie Kosar

A hometown hero, Kosar famously manipulated the rules of the 1985 NFL Supplemental Draft in order to ensure he was able to play for the Browns, which immediately endeared him to the fanbase. He started eight-and-a-half seasons for Cleveland, going 53-51-1 with 21,904 yards, 116 touchdowns, and 81 picks. His Browns teams made the playoffs each year from 185-1989, and Kosar's best season came in 1987 when he threw for 3,033 yards, 22 touchdowns, and nine INTs on his way to a Pro Bowl berth despite starting only 12 games.

Seven games into the 1993 season, then-head coach Bill Belichick released Kosar, citing his “diminishing skills”, which enraged fans. Kosar joined the Dallas Cowboys as Troy Aikman's backup and won the only Super Bowl ring of his career. Kosar may have never quite lived up to the immense hype he received coming of out Miami, but he was a good starter for eight years, which is something to be proud of.

3. Brian Sipe

Kosar's predecessor, Sipe is the only Browns QB to win an NFL MVP. He played 10 years in Cleveland, going 57-55 as starter and leading the team to the playoffs in 1980, his best season as a professional. That year, Sipe finished with an 11-5 record, throwing for 4,132 yards, 30 touchdowns, and 14 interceptions. In his lone playoff action, Sipe threw three picks and no TDs in a 12-14 loss to the Oakland Raiders.

He finished his career with 23,713 yards, 154 touchdowns, and 149 picks. Among Browns QBs, he ranks second in games played, first in attempts, completions, and yards, and second in touchdowns. His 1980 season remains the greatest performance for a passer in Cleveland history.

2. Frank Ryan

A fifth-round pick by the Los Angeles Rams in 1958, Ryan didn't play much as a rookie, and started 11 games over his four seasons with the Rams. After being dealt to the Browns, he took over as Cleveland's starter in 1962 and made three straight Pro Bowls from 1964 to 1966. In 1964, Ryan led the Browns to the NFL Championship, the team's most recent title. His best year was 1966, as he threw for 2,974 yards and 29 touchdowns.

When starting more than three games in a season, Ryan never had a losing record with the Browns, and made four straight playoff appearances beginning in 1964. He is often forgotten by fans, but deserves recognition as one of the team's best signal-callers. He was also a brilliant individual; while in the league, he attended graduate school, and earned his Ph.D. in mathematics from Rice in 1965. That was after earning an undergraduate degree in physics, and that was after he was admitted to Yale, but decided not to attend. He was also an assistant professor during his playing days.

1. Otto Graham

Graham is not only hands-down the best quarterback in Browns history, but has a very good argument as the greatest NFL QB of all time. He spent 10 years in the league, all with Cleveland. He never missed a game, going 57-13-1 as a starter. He led the Browns to the championship game each year, and won seven titles. He totaled 23,584 passing yards and 174 touchdowns, in an era where the forward pass had yet to completely take over. He also added 44 touchdowns on the ground.

Graham made five Pro Bowls and seven All-Pro teams, won three MVPs, and was inducted into the Pro Football Hall of Fame in 1965. To this day, he holds the NFL record for career yards per attempt at 8.63 and career winning percentage at 81%. Graham was flat-out dominant during his time in the league, and as good as the Tom Brady/Bill Belichick duo was for the New England Patriots, the Otto Graham/Paul Brown duo may have been even better for Cleveland.