BEREA, Ohio -- Baker Mayfield has entered uncharted territory for Cleveland Browns quarterbacks.

Since Gregg Williams replaced Hue Jackson as head coach and Freddie Kitchens replaced Toddy Haley as offensive coordinator, Mayfield has had five games in which he completed at least 67 percent of his passes. No other Browns quarterback has accomplished that feat since 1999, the year the Browns returned from a three-year hiatus, according to ProFootballReference.com. Mayfield is also one of only 42 NFL quarterbacks to do that since 1999.

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The most recent Browns quarterback to do this was Milt Plum in the 1959 and 1960 seasons, according to ProFootballReference.com. But Plum threw 14 or fewer times in three of those games, and he averaged 14.7 throws in those six games (the Browns ran Jim Brown a lot back then). Mayfield has done it while averaging 30.6 attempts and throwing more than 40 passes twice.

As good as that is, Mayfield is a long way from the NFL record. Drew Brees had a streak of 14 games in a row at 67 percent. Mayfield’s five are tied for 24th since 1950, the year the Browns entered the NFL.

But Mayfield is a rookie doing what he’s doing, a rookie who didn’t start initially.

"He's gotten better and better by the game," Denver Broncos coach Vance Joseph said. "So imagine this guy next year at this time how good he can be."

Mayfield already has the Browns' rookie record with 19 touchdown passes, and he is far and away the best of the 2018 draft class. Mayfield leads Sam Darnold, Josh Rosen and Josh Allen in yards per game (261.5), completion percentage (64.4), passer rating (93.4), touchdowns (19) and passing yards (2,877).

Any and all improvement from the Browns is fueled, driven and guided by Mayfield, who is justifying every shred of belief that general manager John Dorsey showed in him when he made him the first overall pick. To Williams, the Browns’ belief -- in themselves and in their flickering playoff hopes -- begins with their quarterback.

“That would not happen if it was phony,” Williams said. “It only happens when everybody sees it being sincere. One of the things that we have talked about for a long time is that leadership comes by example first and voice second. Your body language speaks so loud that you can’t hear anything else that anybody else says that comes out of their mouth.”

Baker Mayfield is having one of the finest seasons ever for a rookie quarterback. AP Photo/Frank Victores

In other words, leaders can’t lead if they don’t produce. Breaking down what Mayfield has done and can do in his remaining three games shows the production (all stats courtesy of ESPN Stats & Information, the Browns and ProFootballReference.com):

Mayfield already holds the Browns' record for yards in a game by a rookie, with 397 against Houston. His four touchdowns against the Bengals were a team rookie high. His 19 touchdown passes are also a team rookie record, breaking Otto Graham’s mark set when the Browns were in the AAFC.

Mayfield’s completion percentage for the season is 64.4. Among rookies with at least 10 starts, Mayfield ranks fifth. Dak Prescott recorded 67.8 percent in 2016, Ben Roethlisberger 66.4 in 2004, Robert Griffin III 65.7 in 2012 and Teddy Bridgewater 64.4 percent in 2014.

Mayfield needs to average 170 yards per game to top Brandon Weeden’s team rookie passing yardage mark of 3,385. Ahead of Mayfield is DeShone Kizer, who had 2,894 last season. Mayfield should pass Kizer against Denver.

Mayfield's passer rating of 92.3 would be the best by a Browns rookie (Cody Kessler had 92.3 in 2016) and fifth-best all time (minimum 100 attempts).

Mayfield owns the all-time rookie mark for passer rating in a game, with 151.2 against Atlanta, and he joined Aaron Rodgers and Kurt Warner as the only quarterbacks in NFL history to top 140 for passer rating in consecutive games (minimum 20 attempts).

Mayfield has 10 consecutive games with a touchdown pass, marking the first time a Browns quarterback has done that in a season since Bernie Kosar in 1987. Mayfield has a ways to go to catch Kosar, though; he had 17 between 1986 and ’87. Frank Ryan owns the Browns' all-time record, with 24 such games in a row (1965-67) and is one ahead of Mayfield with 11 in 1963 and ’64.

The only quarterbacks in the Super Bowl era to throw a touchdown pass in their first 10 starts: Warner (1999), Brad Johnson (1996-97) and Mayfield. Dak Prescott holds the rookie record for consecutive games with a touchdown pass with 11 in 2016. Mayfield matched Teddy Bridgewater and Andy Dalton with 10.

Mayfield’s 19 touchdown passes are seven behind the rookie record set by Peyton Manning and Russell Wilson. Andrew Luck and Prescott both had 23. Mayfield has averaged 1.7 touchdowns per game; on that pace, he’d finish with 24.

Mayfield’s next touchdown pass will tie him with Dan Marino for the most touchdown passes in a rookie’s first 12 games (since the AFL-NFL merger).

Mayfield could become the first Browns quarterback since Bill Nelsen in 1968 to complete a pass of at least 60 yards in three consecutive games.

Any or all of these marks would put Mayfield’s rookie season among the best in NFL history. It’s a passing era, but he is doing this with a team that was winless in 2016 and dropped to 2-6-1 after a four-game losing streak earlier this season.

Since then, the Browns have won three of four, and Mayfield’s numbers have been glittering. In those four games, Mayfield has completed 74.8 percent (83-of-111) with nine touchdowns and three interceptions.

Those numbers look that much better with the realization that they include Mayfield’s woeful first half in Houston. He followed that by throwing for 351 yards in the second half, a 30-minute stretch that he and the team might look back on as the most important of the season.

Even with his worst half of the season, Mayfield’s rating was 121.7. Drew Brees leads the league in passer rating, at 120.8.

The half counts, but remove it, and Mayfield’s numbers soar even higher: 81.2 percent (78-of-96) completion percentage, 1,060 yards, nine touchdowns and no interceptions.

Rating: 143.9.