Sam was taken 249th out of 256 picks, by St. Louis. There was applause at Radio City Music Hall from the slim crowd on hand.
Scouts had pegged him to be a mid- to late-round selection, but he didn't perform well at the combine; some questioned whether he would be drafted at all.
The star quarterbacks of the SEC went earlier, but will be long shots to become early starters in the pros.
McCarron led Alabama to two national titles, but had to wait until the 164th overall spot to be selected by Cincinnati. Georgia's Murray went one pick earlier Saturday to Kansas City. LSU's Mettenberger didn't go until the sixth round, to Tennessee.
Virginia Tech's Logan Thomas, not nearly as accomplished as the SEC passers, was the first QB chosen, by Arizona in the fourth round.
Murray had a penchant for big plays with the Bulldogs, but the SEC's career passing leader tore his ACL on Nov. 8 and did not work out during the NFL combine. He figures to compete for a third-string job this year.
"There's no restrictions, no second thought when I'm running, cutting," Murray said. "It's full-speed, full-go ahead."
McCarron expects to learn behind Andy Dalton, who led the Bengals to three straight playoff berths for the first time in franchise history.
"I'm confident in myself, but at the same time, I know Andy's the QB out there and I respect that," McCarron said. "All I want to do is go in and help us in whatever way I can. If that means me holding the clipboard for a couple of years and giving Andy reports during the week and watching film with him and helping him in any way I can, I'm just ready to do it."
Thomas comes out of school healthy, but the inconsistency that plagued his career hurt his draft stock. Thomas never really improved to the level expected with the Hokies after a strong debut. He's big, with a strong arm, but is turnover prone.
"I've grown as a quarterback in this offseason," Thomas said. "Everybody's basing it off the season, which I understand. That's what's on film. But this offseason was a chance I was able to really go refine some things."
Early Saturday, many picks had ties to Clemson star receiver Sammy Watkins.
Watkins, the fourth overall selection in the first round by Buffalo, saw his older brother, Florida cornerback Jaylen Watkins, taken by Philadelphia to open the fourth round. Philadelphia acquired the selection the previous day from Houston, trading its third-round pick (No. 83) for the Texans' fourth- and fifth-round spots.
"Today is a very big day for our family," Jaylen said. "I texted him (Thursday) before he went on stage and he just texted me ... we're both excited for each other. We can't complain about anything that happened this year for us."
The next pick, by Washington, was Sammy Watkins' college teammate, cornerback Bashaud Breeland, who went up against the nation's top wideout in practice for several years at Clemson.
Watkins' fellow receiver with the Tigers, Martavis Bryant, also went in the fourth round, to Pittsburgh.
Andre Williams of Boston College, the nation's leading rusher, went to the New York Giants, whose backfield has been plagued by injuries. Williams rushed for 2,177 yards and won the Doak Walker Award as America's top running back in 2013, but he is considered a weak receiver.
"Patience is a really valuable thing," Williams said. "It worked out the best possible way it could, no matter what round it ended up being."
While the Longhorns were looking for someone to be picked, Duke had a drafted player. When Buffalo made cornerback Ross Cockrell the 109th overall selection, it was the highest a Blue Devil had gone since offensive lineman Lennie Friedman went to Denver in the second round in 1999.
Cockrell thought Duke making the Chick-Fil-A bowl helped his stock.
"I think it opened a lot of eyes that this guy from Duke can actually play a little ball and will be able to compete at the next level," he said.