Sam's very good, but he's not "the best." He can be beaten in one-on-one H2H combat. It's part of why I don't like the "assault" style of gameplay they keep injecting into the game. For all his training, the series has well-established that Sam has little chance surviving a frontal assault with only what he carries into a mission...especially against an unknown quantity of bad guys. He's always relied on stealth to get in and out in one piece. Fighting is a last option, not a primary strategy, for Sam.