One of the most closely-watched training camp battle will be one that encompasses both sides of the field for the San Francisco 49ers -- special teams.

Because the 49ers are so deep, it may be difficult to keep some players who specialize on special teams. They kept a core of special teams player last year, though, and saw a dramatic spike in production from the unit. So, the team knows the importance of keeping quality special teamers.

Here is a look at some players how hope to make the team based on special teams:

Blake Costanzo: The 49ers brought back this special teams ace this season. But he may have difficulty making the roster. If young linebackers Nick Moody and Shayne Skov show both potential on defense and proficiency on special teams, Constanzo will have an uphill battle to make the 53-man roster.

Darryl Morris: Morris has been working at slot cornerback and can take himself off this list of valuable special teamers by gaining the trust of the defensive coaches. Even if he does, he will remain a core special teamer, albeit a more valuable one. Count on it happening.

Lawrence Okoye: This is a special case. Okoye is a major project, but he is so intriguing. He is a fast, huge and athletic. Yet, he is a total green banana when it comes to football. He will need time to develop at defensive tackle. Yet, he stood out in workouts on special teams. He may work his way on the team as a special teamer, while getting seasoning on defense.

Kassim Osgood: He is one of the best special teamers in the NFL. He was a big reason why the 49ers were so good on special teams last year. But there is major logjam at receiver if Brandon Lloyd continues a big training camp and the 49ers don't have key injuries. Osgood could be a victim of the numbers game.

C.J. Spillman: He isn't going anywhere. He is a core special teamer, and can help some at safety.

Bubba Ventrone: Ventrone is like Osgood. He helped the 49ers become good on special teams last year, but he is basically just a special teamer. That could make him vulnerable. But I still think he has a great chance of making it, especially if the 49ers can't find a way to keep Osgood. The 49ers could take a hit without Osgood and Ventrone.