FOXBORO — Andrew Walter didn't say it in so many words, but one gets the sense in talking with the new Patriots backup quarterback that he's pretty happy to have gotten away from the National Football League's version of purgatory and into its nirvana.

The 27-year old Colorado native, signed Sunday night after being released by the Oakland Raiders on July 30, is in the very early stages of learning a thick and quite nuanced offensive playbook — one that holds little resemblance to playbooks he's read before.

"There's not a whole lot of similarities with this and the offense I've been in the past two years," he said. "I've been in a number of offenses in the pros, so you associate terms you're hearing now with what (you've known) from the past. Some of that does carry over, but I will say so far there hasn't been a ton."

Walter sees an "explosive" offense in his early perusing of New England's book, and also feels positive vibes and a great atmosphere from his new team.

The former third-round pick out of Arizona State started eight games for the Raiders in 2006, and had Randy Moss on the receiving end of several of his throws. Fittingly, Walter's first pass of camp with the Patriots, on Tuesday, went to Moss.

Walter said he has a good relationship with Moss, and while the two have spent a little bit of time catching up since he arrived in Foxboro, most of Walter's time has been spent in the quarterback's meeting room and studying.

When the topic turned to his underwhelming career numbers — 3 touchdowns against 16 interceptions and a 52.3 pass-completion percentage — Walter claimed to not want to talk about the past but gave a little insight about his struggles.

"That's something that people who know that situation, they can judge for themselves," he said. "If you do a couple of Google searches, do some research, you can find enough information."

While Walter said that being released two days into training camp was not an ideal situation, he smiled when asked whether signing with New England was a nice turn of events.

"I think that's safe to say," he replied.

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The quarterback Walter replaced, Matt Gutierrez, has hooked on with — surprise, surprise — the Chiefs. He becomes the fourth ex-New England player to join Kansas City since Scott Pioli took over as head of the franchise. The others: Quarterback Matt Cassel and linebackers Mike Vrabel and Vince Redd.

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A team of NFL field officials, headed by 12th year referee Terry McAulay, arrived in Foxboro on Wednesday and will be on hand through Friday morning's practice to give the coaches and players their view of the way players should follow the game's rules.

The four-man crew also met with media after the morning practice. A video outlining the season's rule changes and points of emphasis was shown, and McAulay answered questions.

The wedge ban on special teams and the horse-collar tackle will be points of emphasis this year; according to the video, the number of flags thrown for horse-collar tackles — when a player grabs the inside of a player's jersey from behind to bring him down — doubled from 2007 to 2008.

McAulay fielded a few questions about the so-called Brady Rule, which prohibits the type of lunging-off-the-turf, diving-at-a-quarterback's-knee play from Kansas City's Bernard Pollard that ended Tom Brady's '08 season.

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Former Denver Broncos coach Mike Shanahan was again roaming the sidelines during Wednesday morning's practice, and Bill Belichick said after the session that it was nice to have Shanahan around and talk in a more relaxed situation: "As everyone knows, I have great respect for Mike. It was good to be able to talk to Mike in not a competitive situation where we're trying to beat each other's brains out, but talk football and talk about some team situations and things like that. I think Mike's a tremendous coach."

Shanahan spent a couple of days in New England, and previously in Pittsburgh, observing the franchises. He has said he would be coaching again for the 2010 season.

New home for Gutierrez

Quarterback Matt Gutierrez, cut by the Patriots on Tuesday, has been picked up by the Kansas City Chiefs, where he'll compete to be the backup for Matt Cassell. So, the Chiefs have claimed a former Patriots backup QB to back up a former Patriots QB.

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• In the one-on-one tackling drill, Fred Taylor froze Brandon Meriweather. Taylor may be 33, but he still has some good stutter in his steps as he's shown thus far in camp;

• In 11-on-11 work, there was a rare sight: Moss dropped a ball right on his hands. The pass from Brady was over the middle of the field and there were two defenders close by, but the ball just went off Moss' hands. Later, Brady looked to Moss in the back left corner of the end zone, with coverage from Pat Chung and Mike Richardson, but the ball was short and Richardson was able to bat it away;

• Adalius Thomas had two batted balls of his own, one at the line of scrimmage off Kevin O'Connell's hand, and another when he ranged to his left to swat down a Brady pass. Thomas also had to run a lap for a false start.

• Laurence Maroney had a good goal-line run, flashing a couple of quick cuts on a tough run to the end zone; on the next snap, Brady threw a low pass to Wes Welker, who got down and held onto the ball as he rolled to the grass.

• Richard Seymour, Tedy Bruschi, Shawn Springs and Jonathan Wilhite continue to miss time due to unspecified injuries; Vince Wilfork was not present, but it is believed wife Bianca had planned to have the couple's third child Wednesday; rookie D-lineman Darryl Richard made his camp debut, as he was taken off the active/PUP list;

• The afternoon session was a walk-through.

smanza@projo.com