Bud Grant led the Vikings to four Super Bowls during his 18 seasons as coach and has seen a lot of great running backs.

And Grant said he believes that Adrian Peterson, who rushed for 212 yards in the Vikings' 36-22 victory at St. Louis on Sunday, is the type of running back that the NFL hasn't seen for some time.

However to go down as an all-time great, Grant believes Peterson has to continue what he has done over his first six NFL seasons for a few more years. He has to prove he can compile statistics similar to Walter Payton, the Bears great who amassed 16,726 rushing yards from 1975 to '87.

Asked to compare Peterson with Chuck Foreman, the star Vikings running back of the 1970s, Grant said they are different types of runners.

"[Peterson] is faster than Foreman. But Foreman was a bigger back," Grant said, before pointing out that Foreman only played eight NFL seasons. "... If Foreman had played 10 or 12 years, he might have been one of the greatest of all time."

Grant, a great judge of talent, believes it is hard to evaluate running backs until they are done. The NFL's career leading rusher, Emmitt Smith, played 15 seasons.

Grant said Peterson does have a combination of talents that some great backs of the past didn't have.

"If Adrian can continue to play at this level for a couple, three more years, he can go down as one of the greatest," Grant said. "Peterson has a combination of strength and speed. Not all running backs have that. Some are fast, some are strong, some are evasive, but Adrian has a combination of strength and speed. He can break through tackles, and he can also outrun people."

In Grant's opinion, there is no doubt that Peterson is the best back in the NFL today.

"He's got the statistics to prove that. But how he'll go down in history depends upon how long he can play at this level," Grant said.

No team in the NFL has found a defense that can effectively stop Peterson consistently, Grant said.

"Everybody plays the box [as many as eight defenders along the line of scrimmage], but he bounces outside or gets a crack, and then he's got the speed to run away from people," Grant said. "A lot of the great backs get through there, but they don't have the speed to run away. Once he gets ahead, you can't catch him."

Grant said the only thing Peterson hasn't proven up to this point of his career is how good a receiver he is, because the Vikings don't throw the ball to him very much. As examples, Grant pointed out that Foreman was a great receiver to go along with his other talents, and so was the Raiders' Marcus Allen.

Walsh biggest surprise The other day, I asked Rick Spielman who was the biggest surprise of the Vikings' very successful 2012 draft, and without hesitation the general manager mentioned Blair Walsh.

The Vikings would be subject to a lot of second-guessing if Walsh didn't come through after they had released Ryan Longwell, one of the great kickers in NFL history.

But Walsh continued to make the decision to go with a rookie kicker look very good Sunday when he converted on attempts of 38, 42, 50, 51 and 53 yards.

By kicking three field goals of at least 50 yards, Walsh matched the NFL record with eight in a season. For the season, he is 29-for-32 on field goals, and he seldom fails to send a kickoff into the end zone.

The Vikings gambled when they drafted Walsh because he had his struggles his senior year at Georgia, when he made only 21 of 35 field-goal attempts.

"We had identified him as one of the top kickers because of what he had done previously before his senior year. Coach [Mike] Priefer and coach [Chris] White went down there and worked him out specifically, and basically they are the experts on the kickers," Spielman said.

"And I asked them is this something we can correct, or you can correct, in working with him? They felt very strongly that some of the inaccuracy that he was having his senior year was correctable. We decided to go ahead and take him and we let Ryan Longwell go, who was an excellent kicker for us and very accurate, and so far that has worked out for us."

Spielman said Priefer noticed some technical aspects when Walsh was working out, and when the kicker slowed down his approach, the accuracy came back.

"But I know when we saw him work out at the combine that he was the best kickoff guy through all the kickoff drills. That was one thing we really wanted to hone in on and focus on, was getting our kickoffs better," Spielman said. "If you have a kicker that can at least knock it into the end zone or out of the end zone and get touchbacks, that puts a lot less stress and a lot less pressure on your defense, if they have to drive 80 yards for a score."

Count Grant among Walsh's many fans.

"He's great. From 50 yards, wow, you know, we've got a very good chance of scoring," Grant said. "So the kicking of Walsh and the running of Adrian are keeping us in the playoff picture."

Respects Bradford No doubt Vikings right tackle Phil Loadholt was not surprised to see Rams quarterback Sam Bradford, his former teammate at Oklahoma, throw for 377 yards and three touchdowns.

The Vikings had a 33-7 lead at one time, but once Bradford got hot in the fourth quarter, it looked as if he had a chance to rally the Rams to a victory.

"I played with [Bradford] for two years down there and won a lot of games with him," Loadholt said of Bradford the other day. "He's a real student of the game and I've been impressed with the way he's been playing.

"I think he's a real knowledgeable quarterback. When we were together, he knew what everybody was supposed to be doing. I think his knowledge kind of separates him from everyone else.

"He was a great leader for us, from the time he stepped in to our whole time together. We won two Big 12 championships and went to the national championship. He won the Heisman that year [2008] and had a big year for us."

Sid Hartman can be heard weekdays on 830-AM at 6:40, 7:40 and 8:40 a.m. and Sundays at 9:30 a.m. shartman@startribune.com