49ers depth chart 2014: What's next at guard, center in free agency and the 2014 NFL Draft?

We've already taken a look at what's changed and where we're going with the safety, backup quarterback and inside linebacker positions, and now I'm tagging in to discuss the interior of the offensive line.

The San Francisco 49ers have had one of the premier offensive lines in the NFL for some time now, and its primarily been bolstered by strong drafted or otherwise acquiring rookies.

Joe Staley, Mike Iupati and Anthony Davis are all excellent players and they were all selected in the first round by the 49ers. Alex Boone was going to be a high draft pick before his off-the-field issues, and the 49ers took a shot on him as an undrafted free agent. All four of those players are easily among the top ten at their position, with Boone and Staley easily being among the top five at their respective positions.

Center is the one position in which the 49ers didn't build through the draft. San Francisco targeted Jonathan Goodwin on the open market a couple seasons ago, and he's worked out very well. He's above average and he's not prone to making mistakes, which is about all you can ask for when the other four guys on the line are studs.

Goodwin is currently a free agent, and the 49ers have made no moves to sign him. More than that, they've made no real moves to replace him with an outside choice, either. It's unclear if they were possibly in on some of the other players who have since been signed or not -- but the point is, San Francisco has not brought someone in.

At this point, Goodwin can still return to San Francisco, but he would have to be back on a very team-friendly deal, which may or may not be what Goodwin is willing to accept at this point in his career. But aside from Goodwin is there anything out there on the open market? As it happens, there's not a whole lot.

Of the players currently available, I'd say the only ones worthy of starting are Goodwin and Brian De La Puente. I'd personally love it if they went out and signed De La Puente, but I don't consider it all that likely, really. He's better than Goodwin at this point, but he's drawn interest from multiple teams to this point. I'm uncertain as to why he's still available, so maybe there's more to it than meets the eye.

At this stage in free agency, it might be pertinent to look toward the NFL Draft instead. I don't know that the 49ers would spend a first-round pick on a center, but I could easily see one going in the second or third round. I'm personally not sold on Daniel Kilgore, but things certainly are shaping up for him to start if Goodwin is not re-signed and a rookie isn't quite ready.

Kilgore will likely find one of his jobs in jeopardy next season anyway, so him moving into a starting role makes sense. Kilgore was often the sixth or seventh man on the field in heavy formations (along with Adam Snyder), which might have given the 49ers what they needed to see to determine if they want him to start. Whatever the case, I'd expect them to draft a center to compete with Kilgore, probably in the top four rounds.

For an idea of the top centers entering the draft -- and keep in mind this is always a bit of a murky proposition given that we often see offensive linemen switch positions, especially among the interior, so this list isn't exactly complete. But it's taken from the big board that Fooch has been linking to lately, from NN user Poldarn. I've put the overall ranking in quotes. Check out the full big board and look into the guards as well.

1. Marcus Martin, USC (59)
2. Travis Swanson, Arkansas (87)
3. Weston Richburg, Colorado State (94)
4. Bryan Stork, Florida State (165)
5. Russell Bodine, North Carolina (171)
6. Tyler Larsen, Utah State (188)
7. Corey Linsley, Ohio State (232)
8. Gabe Ikard, Oklahoma (246)
9. James Stone, Tennessee (292)
10. Jonotthan Harrison, Florida (329)
11. Zac Kerin, Toledo (353)
12. Matt Armstrong, Grand Valley State (356)

This post is about the interior of the line, but really, I don't see much use in talking about the guard spots. Mike Iupati is going to be a free agent next season, and Alex Boone is an incredible player. We'll have to address Iupati, whether that means letting him go, re-signing him or what have you. I personally believe the 49ers could be looking at possibly working out Jonathan Martin at the guard spot to see if he might be able to replace him. Whatever the case, free agency is not the place to look for a guard at this point.

San Francisco also has too many needs in the earlier rounds to draft a guard unless a can't-miss prospect falls to them. We'll see how those chips fall in the coming months.