In most Offenses, the Right Guard is usually the bigger, stronger of the two Guard positions and is more capable of matching up one on one. Generally, the RG is not asked to pull or reach two the second level nearly as much. Also, defensively, the speed guy is typically on the weak side or the Left DE. This is where you see more stunts and twists because it's already problematic to get a speed edge rusher blocked. The Offense accounts for that guy so the more times you can create confusion in the blocking scheme on that side of the ball, the more success you might have in getting pressure. That is why the Left Guard is generally more mobile then the RG. It does make a difference. If you have a player who has the ability to pull and lead, who is quicker, then that is Generally the LG. Martin is exactly that guy for us. He is more mobile and quicker then either Bern or Leary. This is why the discussion of which side he best fits is important. I agree, he can play either and is a Pro Bowler then it doesn't matter, if you also have a very capable guy who is already playing LG. We don't have that IMO. I believe that both Bern and Leary are two slow to play LG. It makes more sense to me to use Leary as the primary backup and let the best two Guards Start. I believe that would be Bern on the Right and Martin on the Left.