CHARLOTTE, N.C. -- Russell Shepard spent the early part of this past offseason in the Houston area working out with a quarterback no NFL team seemingly wanted.
The Carolina Panthers wide receiver saw firsthand the frustration this 29-year-old journeyman felt every day that his phone didn't ring.
Shepard called that quarterback a few weeks ago to say how proud he was of him.
The quarterback was Case Keenum.
Many are surprised by the storybook season Keenum is having for the Minnesota Vikings (10-2), who come into Sunday's game against the Panthers (8-4) tied with Philadelphia for the best record in the NFC.
"Hell no," he said on Monday. "I know the challenges of being a guy that's undrafted, a guy that expectations aren't high for you, you don't have the physical skill sets that a first-round pick has and the franchise guy has.
"When you can stay in this league [as long as he has], it says something about your mentality."
Shepard, a native of Houston, has gotten to know Keenum well the past five years. The 27-year-old watched the 6-foot, 215-pound quarterback from 2007 to 2011 set almost every NCAA passing record while playing for the University of Houston.
Shepard can't say enough how much he respects the tenacity that has kept Keenum in the league, how good it feels to see the Abilene, Texas, native do so well in this improbable season.
"The Vikings called him last-minute," Shepard recalled of Keenan's signing just before the start of offseason workouts. "They wanted him, kind of in his mind from what he was telling me, as a camp body, an extra guy, knowing the injuries at quarterback with Teddy [Bridgewater] still being hurt.
"Just to see him take off, man, it's one of those crazy stories."
Keenum was thrust into the starting lineup because of a knee injury to Sam Bradford that ultimately landed Bradford on injured reserve. Keenum has gone 8-2 as the starter after going 9-15 since entering the league as an undrafted free agent with the Houston Texans in 2012.
He was 4-5 for the Los Angeles Rams a year ago, throwing 11 interceptions to nine touchdown passes.
When the Rams gave him his walking papers, his career looked done.
Now Keenum has entered the NFL MVP conversation with 16 touchdown passes to five interceptions.
He has completed 67.5 percent of his passes for 2,703 yards and has a passer rating of 98.6 that is bettered by only six other quarterbacks this season. He ranks ahead of Panthers quarterback Cam Newton, the 2015 NFL MVP, in every major statistical passing category.
He has played so well that he's kept Bridgewater on the bench since the 2014 first-round pick came back from an ACL injury that ended his 2016 season before it began.
Keenum's story has a feel similar to that of former St. Louis Rams quarterback Kurt Warner, who went from stocking grocery shelves to NFL and Super Bowl MVP to the Pro Football Hall of Fame.
"He could be the No. 1 [all-time] undrafted player," Shepard said of Warner.
Undrafted players apparently stick together.
And pull for each other.
"We're like the misfits, like the rug rats," Shepard said. "In this league, in life in general, everybody wants to see the underdog succeed. Everybody wants to see the guy that nobody expected to be that guy."
But what makes Keenum extra-special, Shepard said, are expectations.
There were none.
"At the end of the day, he realizes people expect him to fail," Shepard said. "People don't have high expectations for him, especially him being a part of something that was real ugly in LA last year.
"But when you believe in yourself, that's kind of the formula to have the success he's having.
Shepard saw before the Vikings signed Keenum to a one-year, $2 million deal that the quarterback had what it took.
"He's very even-keeled, a very mild-mannered individual," he said. "His play and how he's handling that unit up there, that position, is kind of how he is off the field. He doesn't get too high. He doesn't get too low.
"Just to see him bounce back, to not have a job a week prior to OTAs -- it's a testament to his mentality and him as a person."
Keenum, like Warner to some degree, stepped into an ideal situation. The Vikings have a solid running game behind a strong offensive line and a defense Shepard says that "may be the best we've played top to bottom."
"Offensively, they're as fine-tuned as you can get," added Shepard, who played quarterback throughout high school and a little at LSU. "It's a good situation for a quarterback that hasn't played a lot to step into."
And Shepard isn't surprised Keenum has taken advantage of the opportunity.
"He's a feisty dude, man," he said. "I'm not surprised at all."