Maul is innately one of the slowest characters in the game. His rank 8 leader ability combined with a fast-modded Sith Assassin can compensate for it by giving him & the rest of his team a chance to move first, lay down a bunch of debuffs, and if that includes stuns then maybe he gets to move again before the enemies do.
Of course the rank 8 leader ability also gives him a good chance to dodge and stealth while he waits for his next turn.
Otherwise it would take incredible amounts of speed stats on his mods to raise his un-buffed speed to the ranks of the mediocre.