ATLANTA – Hall of Fame quarterback Warren Moon has followed Marcus Mariota's career since he first arrived in the NFL.

The two actually became friendly while Mariota was still in college, after meeting at the Davey O'Brien Awards.

Four years into Mariota's career with the Titans, Moon still loves the QB's potential. He's seen enough to convince him he can be very successful in the league. But Moon, who threw for 49,325 yards in 17 NFL seasons with the Oilers, Vikings, Seahawks and Chiefs, believes there are also things Mariota can do to further help himself, from his play, to protecting himself from injuries.

Moon, in town for Super Bowl LIII, also thinks Mariota's development has been slowed because of all the changes around him, especially at offensive coordinator. His health has slowed him as well.

"I've watched his progress, and he's been very impressive at times," Moon said of Mariota. "The biggest thing with him is just staying on the field, and being able to be available every week.

"As a young player, you want to establish yourself as a leader on the team, and be a guy your teammates can depend on and rely on, and it's hard to do that when you are in and out of the lineup a lot throughout the year. Guys want to be able to count on you, especially in the biggest moments, and they want you available to them in the biggest moments. It's a frustrating thing (when you can't play), but injuries are a part of the game, and the way he plays the game – he's not just a passer, he likes to run the football as well – you are going to take a little bit more punishment. Hopefully he can get past some of (the injury issues)."

Mariota missed the team's season finale against the Colts. In 2018, Mariota played in 14 of the team's 16 games, with 13 starts. A lingering nerve injury hampered his play throughout the season.

In his four-year career, Mariota has played in 58 of a possible 66 games, including postseason contests.

Moon didn't escape unscathed during his NFL career. He started all 16 games just four times in 17 seasons, missing stretches because of various injuries. So he feels Mariota's pain.

Moon also offered a few suggestions on how Mariota could help himself.

"First off you just have to be careful – when you do run the football, know when to get down, and when to get out of bounds," Moon said. "And you also have to take really good care of your body. I think that is something Marcus could probably do is put a little more time in the weight room to build himself up a little bit more. He has a long, thin frame, is close to 6-4, around 220 pounds. He can handle a little more weight than that. He could probably put on about 10 more pounds of muscle, which I think would help him, especially with the type of game he wants to play, running the football. And I think it also helps you mentally. It makes you mentally tougher when you know you have the strength and the bulk in your body. That would be one place I would maybe have him look at this offseason: 'Do I want to put on a little more muscle and get a little bit stronger so I can handle the punishment that's going to be out there?' And maybe that will cut down on some injuries."

Moon said all the changes at offensive coordinator have also made things more difficult on Mariota.

The Titans promoted Arthur Smith from tight ends coach to offensive coordinator earlier this month. The second overall pick by the Titans in the 2015 NFL Draft, Mariota will be working with his fifth play-caller in five seasons in the NFL.

While the transition from former OC Matt LaFleur to Smith shouldn't be as drastic as previous years, some things will change that Mariota will need to adjust to in 2019.

"I probably had a stretch where I had three (different offensive coordinators) in a row, but not five, and it's difficult," Moon said. "Because as a quarterback, you want to try and master an offense if you possible can, and it takes a while to do that. You look at some of the great quarterbacks who have played this game, like a Peyton Manning, who was probably in the same system his whole career in Indianapolis until he went to Denver. You look at Tom Brady -- that has basically been built for him. You look at Joe Montana – he was in the West Coast offense with Bill Walsh pretty much his whole career. So when you are able to be in an offense and master that offense, it makes your job so much easier because it takes the thinking part out of it. Now all you have to be able to do is concentrate and focus on the defense.

"But when you are in a new offense all the time, all the nuances of the offense that you are always having to adjust to, or you are always getting used to, not just what your knowledge is of what you do, but what everybody else is doing as well – your receivers, your running backs, your offensive linemen, all the calls you make, all those things… So as a quarterback you want to get to the point where all that thinking is out of the game and you can just focus on what you have to do to attack the defense with the play that's called. And that's where those quarterbacks like Manning, Brady and Montana had a huge advantage as they got later in their careers."

Mariota will enter the final year of his rookie contract in 2019 – the option year.

He's coming off a season when he threw for 2,528 yards, with a franchise record 68.9 percent completion percentage. Mariota also threw just 11 touchdowns, the fewest of his career.

Moon doesn't necessarily believe Mariota is heading into a make-or-break year in Tennessee.

He does believe, however, it's a year when he can answer some questions, while improving. He pointed to Seahawks quarterback Russell Wilson, a player he watches on a regular basis in Seattle.

"Make or break? I don't think it is that drastic," Moon said of Mariota. "I think the team is probably pretty happy with him as a player. I think they probably see more upside in him going forward. … What I'd like to see is him increase the strikes down the field, more touchdown passes. Russell Wilson is a guy I've had a chance to watch for the last seven years, and he doesn't throw it as much as the other quarterbacks around the league, but he is very productive when he does throw it – this year he had 35 touchdown passes. … I'd like to see Marcus be a little more like that, where he puts the ball in the end zone a little more on the attempts he does get, and makes more big plays, more strikes downfield with the throws that he does make even though they are going to run the football predominantly.