He can't just hold closed guard all day. If he is one of those guys that never opens up his guard, he probably has no open guard whatsoever, so the moment he opens for a sub. or sweep you should be able to pass.
Don't try the digging the elbow into the thighs this will only waste energy against someone good and cause your arms to fatigue quicker.
Say he opens for a scissor sweep without controlling your arms, post the arm on the mat/floor (the side of the sweeping leg) I like posting with my fist, digging it into the ground this should block the sweep by keeping your base. Then say if you posted with your left arm bring it under his right leg reach through so you are holding his left leg then with as little space as possible between you and him (While controlling his left hand with your right hand, be sure when you grip do not have your thumb under your other fingers use a four finger grip) start slowly crawling/passing over his left leg while walking his left arm toward his head then establish a good side control
From the closed guard, bring a knee to the center/into his tailbone. If you bring the left knee to the tailbone, then post your arms into his ribcage right at the bottom of the rib cage, make sure your elbows are fully extend post your back straight up then while making sure to keep him pinned with your arms (so he does not ride up your knee and have room to move around) just look back to the left turning your torso toward the left, be sure not to move your arms or lowerbody only move your back and your head moves with your back. If performed correctly this will easily open guard.
Once you open the guard, pin his left leg with your right forearm, and bring your left knee (center knee) across his left leg being sure to put pressure and drive your shin into his leg again as you go over have little to no space between him and you, also be sure to walk his left arm out by controlling his left hand with your right hand. once and only once the center knee has crossed his left leg do you bring your right leg over his left leg and establish sidecontrol (if you fail to correctly cross the left/center leg over before trying to free the right leg anyone any good on the ground will catch you in half guard.) Once opening the guard you can also use the pass I described for blocking the scissor sweep. I always emphasis controlling the wrist as you cross because a really good open guard and half guard player will everytime use that hand to block your hip from coming over and using that base to shrimp back into full guard.
Hopefully you understood this decently, train both passes, use whichever one works for you the best in competion.
I am now having serious Jiu-Jitsu withdrawal so I am off to get ready to go to the gym. Goodluck learning the ground game.
