The Bengals have done fairly well in free agency by re-signing their key players and backups. However, there's still a sizable pool of players left in free agency, including a few former Bengals. You could argue whether or not there are more moves the Bengals should make before the draft, but there's still some holes left on virtually every NFL roster and the Bengals could make a few signings to improve the roster.

At this point, you can say we're approaching the "clearance" phase of free agency, but there's still plenty of quality talent left. In fact, two former Bengals are listed in Pro Football Focus's top eight remaining free agents, as well as one player who they say should be a future Bengal.

The top remaining former Bengals are Leon Hall and Reggie Nelson; unfortunately, as much as many of us would like to see Nelson return to the Bengals, PFF doesn't see it as the best move. Instead, they suggest that the Raiders should sign him, given their success with a veteran free safety last year in Charles Woodson.

Even after a hefty spending spree, the Raiders still have gobs of cap room. The only piece from last year's squad that they've so far been unable to replace is Charles Woodson, and Nelson would go a long way towards dealing with that loss. In terms of coverage grade, Nelson's 83.6 was only slightly behind Woodson's league-leading 86.8.

It also doesn't hurt that they currently have a remaining $20 million in cap space, which is significantly more than what is should cost to sign the veteran free safety who will be 33 in September. Nelson was arguably worth around $5 million per year after his incredible 2015 season in which he led the league with eight interceptions. But, the fact that he remains unsigned isn't doing anything to help his stock.

The fact that he hasn't been signed yet can mean one of two things. First, it could mean that he no longer wants to play football for any team, which would be strange as he has already expressed his desire to return to the Bengals next year. The much more likely scenario is that teams simply aren't willing to pay him what he's asking for, which means he'll have to start asking for less. The Raiders are in a prime position here because they have so much remaining spending money, so they won't have to wait as long as other teams might for Nelson and his agent to start asking for less money.

However, Leon Hall fans will be happy to see PFF's suggestion that he re-signs with the Bengals. Like Nelson, Hall's age and the amount of time he's spent on the open market are working against him in terms of the kind of money he can realistically ask for.

The argument for re-signing Hall is generally that the Bengals don't really have a better slot corner right now. That might be true, but I would personally argue that the biggest reason they should re-sign him has to do with his veteran presence on the defense. The Bengals don't have a lot of cool-headed, reserved veterans on the team who can help bring up the young guys. You could say that the only other defensive player from last year's roster who has those qualities is Nelson, who may not end up back with the team.

The Bengals need a positive presence like Hall on the team to balance out the aggressive one that Adam Jones brings to the table. That's not to say that Jones is a bad influence, but a healthy balance is good to have. One of the biggest criticisms Hall has had in recent years with the Bengals is the amount of salary cap space he's taken up compared to his level of production. Here's the Bengals' chance to retain a good player with a much more team-friendly contract after years of being highly paid.

The Bengals don't generally bring in new potential starters through free agency, but PFF had an excellent suggestion on this end. One of the biggest holes on last year's roster was at center, where Russell Bodine regularly demonstrated sloppy and erratic play. To his credit, he's very intelligent and can call out defensive packages with the best of them. But, his technique when it comes to actually blocking against those packages has become a consistent enough problem that the team should upgrade if they wish to truly put an elite product on the field.

Stefan Wisniewski has been one of the brightest young centers in the NFL since beginning his career in 2011. He was graded as the 12th best center in the league last year by PFF, as opposed to Bodine clocking in as the fourth worst center in the league. In his rookie season, Wisniewski was regularly regarded as one of the best rookie offensive linemen in the NFL. He hasn't slowed down much since, despite playing for some woeful Raiders and Jaguars teams.

Wisniewski is also only 26, which is about three years older than Bodine. There's the possibility that the Bengals want to stick with Bodine because he's young and, if he improves, he could hold down the position for a long time. However, you're not losing much time with Wisniewski, and you're actually gaining a lot of time if you consider how long they could have to wait for Bodine to actually catch up with the NFL defensive linemen he matches up against.

There haven't been any reported talks or interest between the Bengals and Wisniewski so far, so right now this idea is probably just a nice thought that doesn't have much traction. Still, if Wisniewski wants to be a winner, and the Bengals are truly serious about building a competitive squad with the best possible players, this is the right direction.