Before training camp practices last year, Joel Bitonio would pace around muttering his assignments under his breath quietly by his locker. The rookie left guard was anxious and downright nervous on occasion.

Here's the scary part for Bitonio's opponents heading into his second season on the Pro Bowl-caliber left side of Cleveland's offensive line.

"I'm unbelievably more comfortable," Bitonio said.

Of all the contributions the Browns received from rookie players in 2014, none were as heavy-handed as Bitonio's. Sandwiched between left tackle Joe Thomas and center Alex Mack, Bitonio was supposed to stand out because of the inevitable rookie mistakes – except, he rarely made any. Pro Football Focus ranked the 23-year-old as the fifth-best guard in the entire league. He handled defensive linemen and linebackers in the run game and stood like a stone pillar in the pocket as a pass protector.

"Honestly, going into last season, I had high expectations for myself," Bitonio said. "But until you get to the field and start playing, you don't understand what's really happening. I think after the Pittsburgh game, where we kind of ran on them and came back Week 1, I thought, 'I can do this. I can play with these guys.'"

Most younger players around the NFL come with a question mark or two holding their development back. Tweaks to Bitonio's game now are minor, like a faster jump off the snap.

Bitonio and his skills have already crossed the threshold where good players morph into something greater.

"Very competitive. Very coachable," coach Mike Pettine said Friday. "I would be shocked if he doesn't take a big step forward in Year 2, which is saying a lot for a guy who played well as a rookie."

The boost in confidence gives Bitonio time to participate in typical veteran affairs. After a hot training camp practice, the 305-pounder can be found lounging in the cold tub and then the trainer's room for an intense stretching session.

To further illustrate how advanced Bitonio is for a second-year player, the California native also has been handed another imperative task: monitoring first-round pick Cameron Erving.

Of note, Bitonio has instructed Erving on what types of sunflower seeds and coffee the offensive line room likes.

"If Cam doesn't do something right, I get some flak for it," Bitonio said. "Cam is my project."

But Bitonio actually finds himself marveling at the Florida State lineman. How would Bitonio have reacted if the Browns had asked him to learn all five offensive line positions like the Browns have asked of the versatile Erving?

"I would've been angry, probably," Bitonio said. "I would've wanted to learn my position. I would've done it for the team, but it's a tough task. I would've been hesitant. Especially with him going from right guard to left tackle. That's a big, big difference."

The biggest difference will be on Sundays if Bitonio takes the kind of step forward Pettine expects from him. The last time Cleveland had three Pro Bowlers on the offensive line was 1981 (Joe DeLamielleure, Tom DeLeone and Doug Dieken). In today's NFL, that would be an extraordinary number.

If Bitonio falls short of his lofty goal of entering Thomas and Mack territory, he can live in peace knowing this: The Browns want to draft players exactly like him.

"He is all about football," Pettine said. "That to me – you know you are going to be successful when you fill a roster with guys who love to play."