Summer vacation keeps on chugging along for the Browns, but we're spending the weeks ahead of training camp preparing for endless sun rays and seas of brown and orange-clad fans as far as the eye can see through our much-needed sunglasses. Can you feel us wishing good weather into existence in Berea? Us neither (don't jinx it).

While we wait for the players to return and the ball boys to roll out the pigskins, we're previewing training camp by looking at each position. Today's group: offensive linemen.

THE OFFENSIVE LINEMEN

Greg Robinson

Joel Bitonio

JC Tretter

Austin Corbett

Chris Hubbard

Kendall Lamm

Bryan Witzmann

Eric Kush

Kyle Kalis

Brad Seaton

Drew Forbes

Brian Fineanganofo

Ka'John Armstrong

Willie Wright

What we know: Four of the five starters from last year are back, bringing familiarity (an underrated detail) to the group. We know what we'll get out of Bitonio, a 2018 Pro Bowler and one of the league's premier interior linemen. Tretter should be expected to contribute similarly. Hubbard didn't knock anyone's socks off in 2018 but was steady in his first year with the Browns. And Robinson's insertion coincided with the Browns' offensive explosion. No matter his struggle-filled past, that wasn't simply a coincidence. We know this line can largely be counted on, and if Robinson matches last year's play, it could be a top 10 group in the NFL.

What we don't know: There's a big hole to fill at right guard, and we don't know who's going to do it. The general consensus was Corbett's mere presence on the roster as a former 33rd-overall pick would essentially fast-track him to the spot left vacant by the trade that sent Kevin Zeitler to New York, but that hasn't been the case. Corbett has had to battle with a surprise competitor in Kalis and free-agent acquisition Kush, as well as Forbes, a sixth-round rookie. It's very much an open competition heading into camp, so much so that Corbett has also seen reps at center in what could perhaps be a test of how the Browns could use him in the future. A lot of this doesn't matter all that much in the short-term, but finding a starter does matter. Line play is very much based on technique, but also inherently relies on physical activity. We'll get plenty of that when the pads come on in camp and should start to find some clarity along the way.

X-Factor: Tretter. This might be a bit of a surprise -- most would understandably pick Robinson -- but as an intelligent center, Tretter has a lot of responsibility on his shoulders to help whoever wins the right guard job to get acclimated quickly. Expectations are high for this team, meaning the adjustment period must be short for the new starter if the Browns want to get out to a fast start. Tretter's ability to call out protections and also assist his new mate on his right side could go a very long way toward making that acclimation much easier, which would only raise the ceiling for the Browns' offense.

The biggest number: 22. Baker Mayfield was sacked 22 times in his first seven weeks of the 2018 season. Unsurprisingly, the Browns won just two of those games. In his final seven games -- after Cleveland permanently inserted Robinson at left tackle -- he was sacked just three times. This number is the biggest number because keeping Mayfield upright is the line's utmost priority (followed by opening holes for the running backs). If Mayfield is pressured and hit too often, well, we know what will happen. Twenty-two sacks is an unacceptable mark for a seven-game stretch. That cannot happen in 2019.

Says it all: "It is all about versatility. We are trying to find out who has some versatility to them. There is a depth chart of course right now, but at the end of the day, we are trying to prepare all those guys just to compete. Sometimes when you prepare a guy, you have to give him reps, and then when we get back in the fall, we will compete and see who works. ... (Evaluating in pads) is the next step. That is what I was talking about preparing them to compete in training camp because we will have pads on in training camp. From a knowledge standpoint, they need to be prepared to do that so they can put their best foot forward. Then show me what they got. Show us. Show us what they have. You can only do that with pads on." – Freddie Kitchens on the battle for right guard

How many were kept on the initial 53-man roster last year?: 9