[img_r]http://www.packers.com/assets/images/imported/GB/photos/article_images/2010/08-august/100817blackmon210.jpg[/img_r]Head Coach Mike McCarthy often refers to availability being one of the key traits he looks for in players, and for Will Blackmon, who has been limited to just 32 games in four seasons because of injuries, getting back on the field is the first step to him becoming a contributor this season.

Blackmon is working his way back from a torn ACL he sustained in Week 4 last season at Minnesota, and he returned to the practice field on Tuesday morning after being sidelined for the past week and a half because of soreness in his left knee.

I had a chance to watch Will out there today, McCarthy said. He looks really good in the return game. It was good to have him back there. But Will is definitely a factor at the safety position and the corner position. Its good just to get Will healthy and hopefully we can stack some practices with him.

Blackmon, who worked at cornerback in addition to his punt- and kick-return responsibilities his first three seasons, made the transition to safety this offseason. Coming back from a significant knee injury has been challenging enough, but missing reps at his new position only compounded his frustration.

That was the tough thing with me resting, I wanted to get out there and get some reps at safety," he said. "I can sit in the meeting room and go off things and tell the coach that, Yeah, I know this, I know that. To translate that to the field, thats the most difficult part.

The main thing is now instead of me being a corner and waiting to hear the call from the safety, now I am the safety and Ive got to make the call for everybody. That was the biggest adjustment in terms of my preparation. I have to make sure everybody else is all set, and therefore I have to know my stuff double time.

Blackmon said he wasnt aware he would be back on the field on Tuesday until he talked to the doctor in the morning and was given the go-ahead. He lined up at safety opposite Charlie Peprah with the No. 2 defense, and also was first up at both kick returner and punt returner. Defensive coordinator Dom Capers said Blackmons past experience at both nickel and dime could enable him to still see some time in those spots even though he has made the move to safety.

It was funny, I think the first day here, Greg Jennings ran a seam route and he ran right into my chest, Blackmon said. He looked up and he said, Safety? I didnt know you were playing safety. I said, Yeah, theyre not getting rid of me. Im playing everywhere.

(The versatility) helps. We definitely need that depth as the season goes along. Hopefully we dont have any injuries, but you never know, thats how the game of football is. The more guys can do, the better it is.

If Blackmon can get back to full strength, he is expected to regain his position as the top return man, especially on punts. On 47 career punt returns, he has posted an 11.0-yard average and three touchdowns. The three touchdowns match Desmond Howard for the franchise record, who posted that total on 70 returns with Green Bay.

Will is an experienced returner and hes been productive in the past, special teams coordinator Shawn Slocum said. I look forward to strapping it up and seeing what he can do.

Its excitement for me because I know hes a good football player and I know hes a productive returner. I think he adds quite a bit to our return game.

As expected, Blackmon sat out Tuesday night's practice after working in the morning, and he said getting used to having some soreness in the knee throughout the year will be something he will have to get acclimated to. While Blackmon would like to get some game reps during the preseason, especially at safety, his focus is on being back for the regular season.

Its frustrating to an extent, but the one thing I do that keeps me at peace is that I do understand why things are happening, Blackmon said. Its tough when you dont have answers, but I do have the answers as to why certain things are the way they are. Im cool with it. Everybody, Ted (Thompson), Mike, Dr. (Patrick) McKenzie, Pepper (Burruss), everybody is all on board in terms of make sure I do this right and come back full strength.

Im going to be ready for Philadelphia, no question. Its not even a concern about the opener. The main thing is just make sure that I come back strong and do it right. I would say this whole injury is 9-11 months, and Im in month 9. I can sit there and be cool and be prideful and say, Yeah, I came back at seven months, I came back at eight months' and tell them how strong I am. But the bottom line is, six, seven, eight, nine, 10, 11 months, as long as you are ready by the first game, that is the most important thing.

Coming along
Linebacker Clay Matthews, the only defender in Green Bays front seven that was sidelined for the preseason opener against Cleveland, said Tuesday that his rehab for an injured hamstring is progressing well.

Matthews sustained the injury in the annual Family Night scrimmage on Aug. 7, the same hamstring that he injured during USCs Pro Day leading up the draft in 2009, and re-aggravated during OTAs and training camp as a rookie.

When I go inside The Don Hutson Center, I am doing a lot of work, moreso cardio, Matthews said. When I come in here, I am one of the first ones to arrive and one of the last ones to leave as far as treatment is concerned. They have me in here three or four times a day, in here for about an hour to two hours getting treatment.

They are doing everything in their power to get me stronger and back out there. There is a lot of work being put in, and Im sure to the outside you cant see, but Im doing everything within my power to get back.

Matthews described last years hamstring injury during training camp as more frustrating than the current one since he was battling for a starting position and trying to learn a new defense. Matthews missed the first three preseason games last year before returning on a limited basis for the preseason finale, but went on to lead the team with 10 sacks and earn a Pro Bowl berth.

We didnt really set a timetable (for his return), but more how I feel, Matthews said. Barring any setbacks, I think I feel pretty good in coming back, hopefully for Game 3 or Game 4 of this preseason.

Obviously were going to be smart, but at the same time Ill definitely be ready for the season opener.

Injury/participation update
In addition to Blackmon, tight end Tom Crabtree (wrist/hand) and guard/center Jason Spitz (calf) also returned to the practice field on Tuesday morning.

Crabtree left late in the first half against Cleveland on Saturday night after he re-aggravated the injury that has been bothering him since early in camp. Crabtree, who was sporting a cast during practice to protect the injury, said tests revealed that there was no fracture, just a sprained wrist and a bone bruise in his hand, and that it will be just a matter of playing through the pain.

Running back Ryan Grant (concussion) sat out the morning session, but was cleared by doctors around lunch time and returned to the field for the night practice. Linebacker Cyril Obiozor (calf) missed the morning but returned at night.

Veteran tackles Chad Clifton and Mark Tauscher were given the morning off but returned in the evening. One-a-day participants Brett Swain (knee) and safety Derrick Martin (ankle) also sat out the morning session but were on the field for the night practice.

Defensive end Justin Harrell, who was experiencing tightness in his surgically repaired back, sat out both practices.

Continuing to sit out for both practices were running back Kregg Lumpkin (hamstring), linebackers Matthews and Alex Joseph (quad), guard/center Evan Dietrich-Smith (neck), and the three PUP players cornerback Al Harris (knee), safety Atari Bigby (ankle) and running back James Starks (hamstring).