Every year there’s breakout rookie NFL players that not only surprise themselves but also fans, coaches and teammates. Many will enter their sophomore year with high expectations. Some players succeed; some do not.

Last season was filled with a number of good rookies, including quarterbacks and running backs. Many fantasy football players missed out on them for their rosters and now question whether to scoop them up for year No. 2 or not.

Here’s a look at six NFL players likely to hit a sophomore slump in 2013.

RB Alfred Morris (Washington Redskins) – Selected in the sixth round, Morris entered the league under the radar and thrived under coach Mike Shanahan’s pistol-driven offense and his new talented quarterback, fellow rookie Robert Griffin III.

Morris ran for 1,613 yards with 13 touchdowns in his first year, including Week 16’s game against the Dallas Cowboys with 200 yards rushing and three touchdowns.

Now in this second season, Morris’ opponents have had a summer to go through 2012’s film of the player and they’ll be prepared for him. He should still have good production but he won’t match the same numbers.

RB Doug Martin (Tampa Bay Buccaneers) – Martin also entered the league under the radar and thrived on a mediocre team with his combined rushing and receiving yards of 1,926 and 12 touchdowns.

The Bucs made some offseason defensive changes but not to their offensive weapons. Similar to Morris, defenses will now be on look out for this player and he’ll face some tough ones including the San Francisco 49ers, the Seattle Seahawks, the St. Louis Rams and the New England Patriots as well as his usual NFL South foes.

Bucs quarterback Josh Freeman is playing for his job this season. Should he falter, the team could throw rookie Mike Glennon into the mix; this could also change things for Martin. And it may not be for the best.

DE Bruce Irvin (Seattle Seahawks) – Irvin was a first-round pick for Seattle in 2012. He has been suspended for the league’s first four games in violation of the league’s policy for performance-enhancing substances. This means he’ll miss games against the Carolina Panthers, the 49ers, the Jacksonville Jaguars and the Houston Texans.

The Seahawks could be impacted by his absence as 2013 expectations are high for this team. It did bring in two free agent defensive ends, Michael Bennett and Cliff Avril. Add in Red Bryant and the small, speedy Irvin will fight for playing time when he returns in Week 5 at the earliest.

QB Colin Kaepernick (San Francisco 49ers) – Kaepernick burst onto the scene in 2012 when he pinch hit for former 49ers quarterback Alex Smith. He performed so well that he took Smith’s starting job and led his team to the Super Bowl.

In 2013, defenses will have their eyes on Kaepernick. Unfortunately for him, he’ll be without one of his favorite weapons, wide receiver Michael Crabtree, for a lot of the regular season. These two have great chemistry and while they acquired talented receiver Anquan Boldin in the offseason, you have to wonder if these two will have the same bond.

Kaepernick doesn’t like to lose (neither does his coach Jim Harbaugh) but he’ll face some bumps in the road and won’t replicate last season’s production.

QB Ryan Tannehill (Miami Dolphins) – Tannehill is a talented player and in his rookie season, had 3,294 yards and 12 touchdowns. Many think his new offensive weapon, wide receiver Mike Wallace, will help take him to a higher level.

Maybe not as his face challenges from his offensive tackles. Entering the season, Tyson Clabo and Jonathan Martin as the team’s two starting tackles. According to PFF, Martin ranked as the 76th-best tackle last season while Clabo sat at No. 14 at right tackle.

Their roles will likely continue and now protecting Tannehill’s blind side is at stake. He’s carrying the team on his shoulders and could fall under the pressure as well as face blind challenges, resulting in diminished play.

QB Robert Griffin III (Washington Redskins) – This one may come as a surprise but the biggest question facing RG3 is how will he recover from his knee surgery. He’s made phenomenal strides so far with many hoping he’ll be a freak of nature like Minnesota Vikings running back Adrian Peterson and his recovery from knee surgery.

Griffin’s mobility is key to his game and whether he’ll have the same with his recovering right knee is yet to be seen. This player can also run and he likes to play with versatility and take matters into his own hands.

Defenses will have his number more this season and RGIII will exit the starting gate more cautiously than he wants this season. He could rely more on the passing game this season which result in him taking a step backwards before taking ones forward.