Size does matter, but not always in the case of measured strength. It's the perception that some one is strong because they are bigger than the next guy. It's also the perception that BB'ers (not PL'ers or Olympic lifters) are after when seeking larger muscle mass. Bigger animals tend to be stronger and leaders of their pack. That's how the general public see's a larger, muscular people unconsciously. Relating size to strength. Arm, chest and shoulder size usually suggest a strong person to the average man on the street. May be the reason so many men who take up BB'ing will only work the arm's (curls), chest (BP) and shoulders (laterial raises). If some one ask for them to show their muscle, they will flex the biceps. Humans are influenced by that primative belief that bigger is always bette and stronger.
A middle weight lifter (not always on the muscular side) should not be able to Bench 400, but they can and do. Taken to another level, a women (the weaker sex?) can never Bench 400, but some can and do. Strenght is not always geared to any muscle size ratio. Tendon/ligament/joint structure, as well as muscle inserts and bone leverage/density all play a part. Along with a correct balance of strength muscle fibers. Good Luck.
Side Bar: I would bet a lot of 20" guns could not curl a 90lb DB if their life depended upon it. At least from what I have seen first hand. But I have seen a 6'1 guy, weighting in at 181 cheat curl a 205 BB.