TEMPE, Ariz. -- Before Arizona Cardinals starting right guard Evan Mathis could walk off the field after injuring his left foot in the second quarter Sunday night, Earl Watford grabbed his helmet and headed in.
Before Mathis went down, Watford stood on the sideline waiting patiently. It is, in some ways, a hapless job. One of his brethren on the offensive line must go down for Watford to see the field. But fortunately for the Cardinals, Watford can play all five positions across the offensive line.
That's why he's called the Swiss army knife.
Watford, 26, is 6-foot-4 and 300 pounds, likes craft beer and enjoys playing Pokemon. He can also single-handedly change the Cardinals' approach on game day. With teams allowed to dress 46 players, his versatility could allow offensive coordinator Harold Goodwin to feel comfortable with seven offensive linemen, if needed.
That could, in turn, give another position extra depth. On the Cardinals' first two depth charts of the season, Watford was listed as the backup at left guard and left tackle. Rookie Cole Toner was listed as the backup right guard, but he was inactive Sunday.
And that's why Watford has become one of the Cardinals' most valuable players.
"We'd like to only dress seven linemen on Sunday," coach Bruce Arians said in June. "If you can play three spots, you have a lot of value in this league. You can play for a long time.
"If he can handle the center position, it's more hats off to him. That's just better for him we don't have to dress eight guys."
Although his versatility has drawn praise from his coaches, this isn't how Watford pictured his fourth NFL season. Like most draft picks, when Watford was taken in the fourth round in 2013, he envisioned a starting job. But he is open and honest about his career not living up to his expectations, and he said he has been frustrated with how his career has gone.
"Very," he said. "Still am."
It's not the physical side of football that embattled Watford early in his career. Strong, muscular and athletic, he came into the league with the body of a veteran. He has quick feet and an ability to get into the open field to block. His athleticism landed him a spot on the Cardinals' kickoff return team this year.
Rather, it was the mental side of football -- the playbook, the scheme -- that stunted Watford's growth.
"It's a battle," he said. "Every player goes through it, battling with something, whether it's playing time or just how you handle yourself at practice, putting in that extra work.
"Just hasn't panned out the way I envisioned it, but at the same time, that's my fault. No one else to blame. Wasn't good enough. Didn't do enough. So every year I've tried to grow as a person, a player, a professional. Hopefully from here on out it just keeps … it can only get better."
It might have taken Watford four years to get here, but he has finally found a role. He waited during his first two seasons, playing just seven snaps.
His break came last season, when right tackle Bobby Massie was suspended the first two games for violating the league's personal conduct policy. Watford put his improvement on display during training camp and replaced Massie, playing 112 snaps the first two weeks. But he played just 79 snaps the rest of the season.
But while the snaps didn't come in games, they came in practice. Watford worked at tackle and guard all of last season, and then began taking reps at center during OTAs this year. He'll be the emergency center behind A.Q. Shipley and Evan Boehm on game days.
His versatility grew when he started the Cardinals' final preseason game at left tackle, playing the position in a game for the first time. Watford learned one thing after playing two series protecting quarterback Matt Barkley's blind side.
"I can do it," Watford said. "So that was exciting."
While Mathis' diagnosis is unknown, Watford said he feels comfortable about possibly playing in Mathis' place. Watford played left guard in college and in the NFL, so transitioning to right guard is a matter of flipping his technique.
"Just got to focus on technique and get my hands on guys and play hard," Watford said. "No penalties. That's the big thing. Just go out there and do what I'm supposed to do and help the team."
When Watford finished his third season in January, he knew how to play right tackle, right guard and left guard. Learning center and left tackle wasn't as easy.
He spent time at home watching film, studying his playbook and reviewing his notes, trying to master tackle and center as quickly as possible while fine-tuning his guard skills. At practice, Watford asked questions to center Shipley, guards Mike Iupati and Mathis and tackle Jared Veldheer.
Watford knows himself. If he gets too serious, too consumed, too stressed, he'll start to panic. Panic leads to mental errors. Mental errors lead to the bench. The bench leads to unemployment.
"So I crack jokes," Watford said.
While it's not his dream job, being able to play all five offensive line positions is a niche that could keep him on an NFL roster for the next decade.
"Until you can play one position, you have to play multiple positions," he said.
"I'm still a work in progress. I still got a long way to go to perfect these things. I mean, it's kind of like you get thrown in there and got to get it done, or you get fired. It's either do it and do it well, or you won't be around. It's kind of how my mindset is."