Is C.J. Mosley not the NFL's top rookie defender?

Baltimore Ravens inside linebacker C.J. Mosley made 21 more tackles than any other rookie in the NFL. He was named the NFL's top defensive rookie in two of the four months this regular season.

So, Mosley has to be a slam dunk to win NFL Defensive Rookie of the Year, right? Not necessarily.

The league won't announce its end-of-the-year awards during the NFL Honors show on Jan. 31, the night before the Super Bowl, but the Pro Football Writers of America named St. Louis Rams defensive tackle Aaron Donald its NFL Defensive Rookie of the Year.

Donald led all rookies with nine sacks in 2014, a total that ranked second amongst all defensive tackles -- trailing only Buffalo's Marcell Dareus -- and the sixth most by a rookie defensive tackle since sacks became an official statistic in 1982.

Mosley has a strong argument as well, because he was the only NFL defender to post at least 125 tackles , three sacks and two interceptions in 2014.

If Mosley wins NFL Defensive Rookie of the Year, he would become the third Ravens player to earn the award, and the first since linebacker Terrell Suggs in 2003.

Mosley isn't the only Ravens rookie to make an impact this season. Defensive tackle Timmy Jernigan, a second-round pick, was named to the PFWA all-rookie team along with Mosley. Jernigan finished with 23 tackles and four sacks in 12 games played, including three starts.

The Ravens were one of six teams to get two players named to the all-rookie team this season.