With free agency looming in March, roster turnover isn't far away. However, the majority of the 2019 roster is already in place. In the coming weeks, DallasCowboys.com will feature players who are currently under contract for next season, analyzing their past season and their future prospects.

Today, we continue the series with guard Zack Martin.

What's Been Good: What else is there to say about Zack Martin that his trophy case can't say for him. The 2018 season was his fifth in the NFL, and for the fifth-straight year he was named both a Pro Bowler and an All-Pro. He has literally been an All-Pro from the moment he stepped into the league. What made this season so impressive is that he played at a high level despite a debilitating injury. Martin battled knee problems nearly all year long. He hyperextended his left knee in an Aug. 19 preseason game, sidelining him for the second half of the preseason. Weeks later, he sprained his knee in the Cowboys' Oct. 21 loss to Washington. That injury would bother him throughout the second half of the season, eventually forcing him to miss his first-ever NFL game on Dec. 16 against Indianapolis. Despite all of this, Martin played 83 percent of the Cowboys' snaps and was flagged just one time all season, a false start.

What's Been Bad: Not even Zack Martin can play a completely clean season on one healthy leg. There were times where opponents were able to push him back, likely due in part to injury, and there were times he didn't display the effortless athleticism that has come to define his game. In the overtime win against Philadelphia on Dec. 9, Martin surrendered two sacks, which is more than he has typically allowed in a single season. Still, given the injury he was battling through, and the level of play he managed to maintain, this feels like nitpicking. No one in their right mind would classify Martin's play as "bad."

2018 Highlight: Strictly speaking, Martin might've had better pure blocks in 2018, but it's so much fun to watch his effort and athleticism on screen passes. During the Nov. 29 win against the Saints, Martin kicked out to the flat on a short screen to Ezekiel Elliott. Right at the catch point of the pass, the All-Pro guard was in position to completely wipe Saints linebacker Demario Davis out of the play. If Martin misses the block, it's likely a tackle for loss – or worse, perhaps a turnover. Instead, the block sprung Elliott for a 16-yard touchdown. Its was the Cowboys' only touchdown in the 13-10 win.

What's Next: Martin was named to the Pro Bowl in 2018, but it was the first year he didn't actually participate in the all-star game. That's understandable, considering the injuries he fought through – but none of those problems are considered serious. Given a chance to rest and recuperate, there's every reason to believe Martin will continue to play at his usual, All-Pro level well into the future. After signing a massive extension last summer, Martin is widely thought of as the best guard in football and should be a major piece of the Cowboys' roster for years to come.

Bryan Broaddus' Bottom Line: Outsiders will say Zack Martin didn't have one of his better seasons, but those same folks don't have a clue of the issues Martin played through. Despite not being at full strength while dealing with a knee injury, Martin still was one of the better performers on the club. Where his injury affected him was with his mobility, especially in space. There were snaps where you noticed he was a tick slow to the second level as a run blocker or struggling to get in position for the screen. Playing in space is one of Martin's best traits, so you tend to notice when he's struggling there. Where Martin didn't struggle was helping Joe Looney get through what could have been a difficult time. When the news about Travis Frederick broke during training camp, I really expected the worst, but Looney played well -- and in large part that was due to having a guy like Martin right next to him. Martin gave Looney confidence that he could take some chances blocking and Martin would be there to clean up the mess if necessary.

**Click HERE for more Star Evaluations**