The Patriots open organized team activities Monday in Foxboro, a series of 12 practices that will run on-and-off for the next month or so leading up to mandatory minicamp in mid-June. While these sessions are meant to be non-contact affairs — which means little can be gleaned when it comes to measuring real football shape, physicality and, to some extent, speed — there will be a number of things worth watching. Here are five things we’ll be keeping an eye on (the media has access to four practices):

Torry Holt: One thing we did see last spring was that even then, Joey Galloway and Tom Brady looked out-of-sync. At the time, it could have been chalked it up to a number of things — Brady was just coming off a knee injury, it was the first real series of practices together, the quarterback and receiver always need time to develop a chemistry, etc., etc. But in truth, it was the first real signal that the quarterback and the wide receiver simply weren’t copacetic. As a result, the early stages of the professional relationship between Brady and Holt will certainly bear watching.

“I said all season — when I had an opportunity to speak on it — I said I wanted to play with an elite quarterback, and Tom is one of those guys,” Holt said. “You’re talking about a guy who’s tough, he’s passionate, he’s well respected by his teammates.

“I understand his work ethic and his commitment to film study. His improvement every day, every year is outstanding,” added Holt. “I look forward to being around that energy he provides and that leadership and that excellence he exudes. I look forward to being around that.”

In that same vein, the entire wide receiver group is worth focusing on. Presumably Welker will not be out there, so who is taking the majority of snaps at the slot receiver position? After spending most of the year on the shelf because of a knee injury, can Brandon Tate deliver? Can David Patten wake up the echoes and return to greatness?

Previously injured linebackers: After two years on the shelf because of injury, Shawn Crable recently pronounced himself ready to go this season. The Patriots need pass-rushing help, and the Big Fella (6-foot-5, 243 pounds) will have every opportunity this spring and summer to show he can make a real contribution when it comes to getting after the quarterback. If he is going to make an impact in 2010, that process will start this week.

Like Tate and Crable, inside linebacker Tyrone McKenzie was kept off the field because of injury in 2009. The South Florida product was sidelined because of a knee injury he suffered during rookie minicamp last season. Speaking last week with reporters, he was clearly fired up about getting on the field.

“I’m very strong, I’m very fast. I have a lot of assets that are part of my game. You guys can fill in the blanks,” McKenzie told reporters who asked about his health. “I’ll give you plenty to write about. I just have to get on the field first.”

The rookies: The first chance for the new guys to rub shoulders with the veterans always provides an interesting contrast — you have veterans lining up alongside guys who have been thrown into the deep end of the pool. You have to take everything you see at these spring practices with a grain of salt, but you can tell a lot about a rookie depending on how he carries himself in the early stages of the teamwide practices. Most of the time, even the best rookies appear mostly overwhelmed. But what the franchise is looking for is marked improvement between the start of OTAs in May and the time minicamp ends in June. (Bottom line? The coaches understand rookies might be running penalty laps in May and June. If they are running them in training camp in July and August, that’s a bad thing.)

“The thing about our guys is most of our players are very experienced players on their college teams,” Patriots coach Bill Belichick said of this year’s rookie class. “Some of them were seniors or third- or fourth-year juniors — whatever it was — and they were some of the best players on the team and they were most experienced. Now, they’re the least experienced. Now, they’re freshman all over again. The elevator starts at the bottom and they have to ride it up again.”

While all the first-year players will be under the microscope, the area really worth watching will be at tight end, where two rookies (Aaron Hernandez and Rob Gronkowski) will work with new veteran acquisition Alge Crumpler in New England’s latest attempt to remake the tight end position. In addition, first-round pick Devin McCourty enters a crowded picture at cornerback, but rookie linebackers Jermaine Cunningham and Brandon Spikes will almost certainly get an opportunity to make an immediate contribution at linebacker.

Special teams: There was plenty of emphasis on special teams during the recently concluded rookie minicamp — the quickest way for many of the rookies to make an impact will be as special teamers. But there is plenty to watch for over the next month especially when it comes to specific special teams spots. With punter Chris Hanson presumably out the door, Zoltan Mesko and David King will battle over the punters job. In addition, the Patriots would like to resolve a murky situation as a kick returner. Does McCourty — one of the most electric special teamers in the college ranks last season — get a chance to work at all in the return game?

Logan Mankins: The Patriots and the Pro Bowl guard have reportedly been working toward a new deal, but in the meantime, Mankins has apparently steered clear of all offseason activities to this point, balking at the one-year, $3.268 million restricted free agent tag. Technically, he doesn’t have to show up because he apparently has yet to sign his tender, but his absence would still raise eyebrows — over his five years with the Patriots, Mankins’ durability and all-business approach have created a legacy. As a result, it’s news now when he doesn’t show up for something, even something like this.

The big day to keep in mind for Mankins’ deal is June 15 — the first scheduled day of New England’s mandatory minicamp. If he hasn’t signed the deal by then, the Patriots can drop his RFA tender to 110 percent of last year’s salary ($1.5 million).