Shortly after filling another need by re-signing receiver Jerome Simpson to a one-year deal, Vikings General Manager Rick Spielman surfaced via conference call Friday afternoon to declare the first seven days of free agency a successful venture that upgraded the league's worst scoring defense and gave the franchise the flexibility it needs to stay true to its draft board come May.

"We had a specific plan in place," said Spielman, "and we're very pleased how that plan came together."

The plan started on Day 1 of the three-day negotiating period on March 8, when the Vikings re-signed quarterback Matt Cassel and defensive end Everson Griffen. Both were important, but the Cassel re-signing set the tone because the Vikings weren't sure he'd come back after opting out of his previous contract. And that was discomforting for a team that could be ill-positioned to take a quarterback in the first round.

"I think that was a huge piece to this whole thing," Spielman said. "That got us going in the right direction."

Adding nose tackle Linval Joseph and cornerbacks Captain Munnerlyn and Derek Cox infused three youngsters into an aged defense, while Simpson, who was second on the team with a career-high 726 yards receiving last season, gives the Vikings four experienced receivers under contract.

Holes in the roster remain, with the most obvious being left guard, where the team still is pursuing free agents, including incumbent Charlie Johnson. But one week into free agency, Spielman feels comfortable that the moves he's made will enable him to draft the best players available, regardless of position.

"It sure helps you head into the draft not to get boxed in [where] you've got to take this position," Spielman said. "Now we have that flexibility to see how the draft is going to fall. … We feel we have a good start, but by no means is this what our 53-man roster is going to look like."

Although the Vikings now will shift into the next phase of free agency, the action won't come to a standstill. Spielman said the team has some free-agent visits scheduled for next week and will be monitoring the market, looking for bargains that could be had for one-year deals and trying to project which players might end up being post-June 1 roster casualties.

"It's pedal to the metal," Spielman said. "It never ends. That's the exciting part because this is the time of year with free agency and the draft that you've got to improve your ballclub. … We're not saying by any means that we're completely finished, because you don't know what's going to happen."

Spielman also touched on a variety of other topics. Here are some highlights:

On the new run-stuffing nose tackle Joseph not getting enough credit as a pass rusher: "People say, 'Oh, he's a great run stuffer,' but he's very athletic for his size. In fact, we had him in here for a top-30 [visit in 2010] when he was coming out in the draft. We feel not only is he going to help us stop the run, but also has enough power and athletic ability, enough quickness to get upfield as a pass rusher."

On whether he has ruled out bringing free-agent defensive tackle Kevin Williams back for a 12th season: "I've talked to his agent a few days ago. We're continuing to monitor that. There's no decision that's been made. I told him we'd leave it open, that we were trying to address some other needs that we definitely wanted to get done first."

On his plans at left guard and whether they include Johnson or Jeff Baca, a sixth-round draft pick a year ago: "We're excited about where Jeff has come. We're working to try and sign Charlie back. I know he's got a couple of teams that are interested in him as well. I think the more depth you can accumulate on that offensive line, it really helps your ballclub. That's an area that we'll probably address in the draft as well. ... But we'd love to have Charlie Johnson back as well."

On Bears free-agent defensive tackle Henry Melton, who left his visit with the Vikings without a contract and continued on with his plan to visit Seattle and Dallas: "[He wants] to see what's out there, but we've contacted his agent as well and just monitoring it as it goes along."

On quarterback Christian Ponder's future: "Christian is under contract here. He'll be out here participating when we get out here on April 7. I know he's going to get an opportunity to compete."