For just a moment, it looked as if his chance of being picked by a pro team and becoming the league's first openly gay player might take a detour. Or at least be delayed.
The call finally came in Saturday from the St. Louis Rams, the team right down the road from where Sam played his college ball at the University of Missouri.
Sam was selected in the seventh and final round and admitted it was a frustrating wait. He said teams that passed on him chickened out and he should have been drafted sooner.
"From last season alone, I should've been in the first three rounds. SEC Defensive Player of the Year, All-American," Sam said. He stopped short of directly saying his stock dropped in the draft because he came out.
"You know what, who knows? Who knows? Only the people who sit in the war room know," he said. "They saw Michael Sam, day after day they scratched it off the board. That was their loss. But St. Louis kept me on that board. And you know what I feel like I'm a (Jadeveon) Clowney, a first draft pick. I'm proud of where I am now."
Sam came out as gay in media interviews earlier this year. His team and coaches knew his secret and kept it for his final college season. He went on to have the best year of his career: He was the co-defensive player of the year in the nation's best college football conference and had 11.5 sacks.
The pick came after several rounds of suspense. The first round of the day, No. 4 overall, came and went, no Sam. Then the fifth and sixth, and finally, the day was down to just a handful of picks.
When Mike Kensil, the NFL's vice president of game operations, walked to the podium at Radio City Music Hall in the draft's final minutes to announce the Rams' second-to-last pick, the crowd got a sense something was up. Very few of the last day picks were announced at the podium. Twitter lit up with suggestions the Rams were about to make news.
When Kensil said: "The St. Louis Rams select ... Michael Sam..." the fans gave a hearty cheer, chanting "Yes! Yes! Yes!" and "Michael Sam!"
Sam was in San Diego watching with friends and family at the home of his agent, Joe Barkett of Empire Athletes. ESPN and the NFL Network had cameras there and showed Sam's reaction.
Sam was on the phone bending over, with his boyfriend hugging him and rubbing his left bicep. When Sam got off the phone, the tears started. He gave his boyfriend a big kiss and a long hug as he cried and his eyes reddened. After, they shared cake — and another kiss.
"Thank you to the St. Louis Rams and the whole city of St. Louis. I'm using every once of this to achieve greatness!!" Sam tweeted with a frenzied typo moments after he was picked, with a picture of himself wearing a Rams cap and a pink polo shirt.
The 6-foot-2, 255-pound Sam was considered a mid-to-late round pick, far from a sure thing to be drafted. He played defensive end in college, but he's short for that position in the NFL and slower than most outside linebackers, the position he'll need to transition to at the professional level.
He was taken with the 249th overall pick out of 256. Players from Marist, Maine and McGill University in Canada were selected before Sam.
"In the world of diversity we live in now, I'm honored to be a part of this," Rams coach Jeff Fisher said during an interview on ESPN.
The NFL had no comment on Sam being drafted.
The impact of Sam's selection goes far beyond football. At a time when gay marriage is gaining acceptance among Americans, Sam's entry into the NFL is a huge step toward the integration of gay men into professional team sports. Pro sports have in many ways lagged behind the rest of society in acceptance.
"Michael Sam wouldn't have been drafted five years ago," said former Viking punter Chris Kluwe, who has accused Minnesota of cutting him in part because of his vocal support for gay rights.
In the last year, NBA veteran Jason Collins has come out publicly as gay, and is now playing for the Brooklyn Nets. Collins said before the Nets' playoff game against the Heat that he was watching the draft and texted Sam after he was picked.
"It's a great day for Michael and his family and for the NFL," Collins said.
Publicly, most people in and related to the NFL have been supportive of Sam. NFL Commissioner Roger Goodell has said Sam would be welcome in the league and judged solely on his ability to play. A few wondered whether teams would be reluctant to draft Sam because of all the media attention that would come with it.
Fair or not, the NFL — coming off a season in which a bullying scandal involving players on the Miami Dolphins was one of the biggest stories in sports — was looking at a possible public relations hit if Sam was not drafted. He would likely have been signed as a free agent and given a chance to make a team in training camp, but to many it would have looked as if he was being rejected.
Now that he's there, it could be seen as an opportunity for the NFL to show that crass locker room culture is not as prevalent as it might have looked to those who followed the embarrassing Dolphins scandal. But all the reaction to Sam's news wasn't positive from the league.
Miami safety Don Jones posted a one-word tweet, "Horrible" shortly after Sam was drafted. It was later taken down. The team's general manager said he was aware, and was disappointed.
Wade Davis, a gay former NFL player who is now the executive director of the gay rights advocacy group "You Can Play," said that Sam only needs to do his job to have an impact beyond the field.
"Michael Sam doesn't have to be a vocal advocate (for gay rights)," Davis said. "His visibility is his advocacy."