2013 NFL Combine, Day Four: Arrivals, schedule and who to watch

The final group of players arrived in Indianapolis on Saturday as defensive backs get to town. They will be the last ones to work out as they get on the field for workouts and drills on Tuesday.

The 49ers have plenty of players to consider as they look to boost their secondary depth. Their decisions at safety will depend in part on how they address Dashon Goldson's contract situation. I think they still look to add a safety to compete with C.J. Spillman and Trenton Robinson behind Goldson and Donte Whitner, but they did not invest so much in Robinson that they can't look even higher for a long-term option as needed.

For now, here are Nick and Trevor's respective looks at the defensive backs they will be keeping an eye on over the next few days.

Defensive Backs

Robert Alford, Southeastern Louisiana - Alford is one of the fastest players in this year's draft. The small school cornerback had an impressive Senior Bowl and was able to impress scouts with his fluidity. His technique is above average and he could be work his way into the top five at his position with another solid outing in front of scouts.

Nickell Robey, USC - Listed at only 5-8, Robey needs to pray he grows an inch before measuring in. Considering only one CB was drafted last year under 5-10, Robey will have his work cut out for him. He's an excellent athlete and a track star with speed to spare. He plays hard and surprisingly physical for his size. Should test well and his athleticism will likely entice a team to grab him in the later rounds.

Phillip Thomas, Fresno State - Thomas might be one of my favorite players in the draft. If he played at a bigger school, I'd be willing to bet he'd be a first round pick. Thomas isn't expected to light it up in 40 but he tends to play faster than his timed speed indicates. Very instinctive player that would be my #1 choice to replace Dashon Goldson should he be let go.

Shamarko Thomas, Syracuse - Another Thomas that I really like this year. He's a bit undersized for a safety at just under 5-10. Thomas doesn't let his size prevent him from making big hits. He plays with a relentlessness that scouts admire. He also ran a sub 4.4 in the 40 while at Syracuse. Should he duplicate those efforts he could be a day two pick.

Defensive Backs

Tyrann Mathieu, LSU - The Honey badger didn't play this season, so he has a lot to lose or a lot to gain at the combine. He currently projects anywhere from a 3rd to 5th round selection. Tyrann must run a decent 40 yard dash to be considered a legitimate option at cornerback in the NFL. Many scout feel a conversion to safety for him is likely.

Matt Elam, Florida - I picked Elam to go to the 49ers in the first round in our Mock draft 1.0. I'm looking for Elam to back that selection up with a strong performance at the combine. Elam is probably the hardest hitting safety in this draft and he has shown he can compete against big time competition in the SEC.

Desmond Trufant, Washington - Nick had Trufant going to the Niners in our Mock Draft 1.0. There's a lot to like about Trufant and I feel he is a lock as a first round selection. Trufant is known for his excellent zone coverage, but I feel he is equally as good in man coverage. Trufant is a corner who likes to play press coverage and get his hands on the receiver at the line of scrimmage. He's the kind of cornerback the 49ers like, he'd fit their scheme well.

DAY 4 ARRIVALS: Group 10 (DB), Group 11 (DB)