Him pulling that ball down and running was huge. He needs to do more of that. Adds another dimension and something else for the defense to be concerned about. Might even buy him more time on those 4 man rushes as guys try to stay in their lanes to prevent a scramble.
When the kid decides to tuck the ball and run he almost always has the first down or decent yardage at the bare minimum. Instead of forcing throws or simply throwing it away, I'd like to see Tannehill take off and slide for some extra yards every once in a while. Like you said, it adds something to his game and it creates problems for defenses.