Sam Monson of Pro Football Focus created a list of the top 25 players under 25 years old, and two young defenders represent the San Francisco 49ers. All-Pro linebacker Fred Warner (age 24) tops the ranking at No. 1 overall.
"At a position that has become ever-more difficult to play, given how good NFL offenses have become at attacking defensive weaknesses, Warner has become arguably the game's best linebacker," wrote Monson. "The former third-round pick earned a PFF coverage grade of 91.1 in 2020, allowing a passer rating of just 81.9 into his coverage, some 25 points lower than the average at the position."
San Francisco made Warner a third-round selection out of BYU in 2018. He registered 125 tackles, five tackles for a loss, seven quarterback hits, a sack, six passes defensed, two interceptions, and a forced fumble through 16 games with the 49ers last season.
Warner is entering the final year of his rookie contract and will likely soon become one of the league's highest-paid linebackers.
The second 49ers player on the list is pass rusher Nick Bosa (age 23), who comes in at No. 5. The 2019 NFL Defensive Rookie of the Year missed most of last season after suffering a torn ACL during Week 2.
"We have only seen one year of Nick Bosa in the NFL, with injury robbing us of an encore last season," wrote Monson. "Still, that one year was devastating. As a rookie, Bosa notched 80 total pressures, breaking the PFF rookie record. He was still cooking by the Super Bowl, too, where he notched 12 pressures in a losing effort to try and contain Patrick Mahomes and the Kansas City Chiefs."
That dominating rookie campaign also included 47 tackles, 16 tackles for a loss, 25 quarterback hits, nine sacks, an interception, two passes defensed, and a forced fumble. Bosa added four more sacks during postseason play that season.
All-Pro tight end George Kittle offered high praise of his defensive teammate while speaking on the Rich Eisen Show last month.
"I think I've said this about 100 times; I still think Nick Bosa is like the second-best NFL player behind Aaron Donald, and I think he's going to come back with a vengeance," Kittle told Rich Eisen. "And I'm very excited about that because he's a very talented football player, and he definitely makes that defense gear up a whole extra notch."