I agree that the only ambiguity is whether Middlebooks raising his legs could be interpreted as an attempt to obstruct the runner. However, it seems the umpires made it clear that this is not what they were calling when they emphasized that there is no intent requirement in the rule. They are totally wrong though: "If an infielder dives at a ground ball and the ball passes him and he continues to lie on the ground and delays the progress of the runner, he very likely has obstructed the runner." The use of the qualifier "very likely" clearly suggests that there are situations where the fielder has missed the ball (i.e. no longer in the act of fielding the ball) and yet he is NOT guilty of obstructing the runner. The strict liability interpretation advocated by the umpires and by many online is logically inconsistent with that language. Either the rule is written incorrectly, or there is an implied intent requirement such that "continues to lie on the ground" means a deliberate and opportunistic attempt to impede the runner, not an involuntary consequence of an attempt to field the ball. That is also the plain meaning of "and he continues," it suggests that the fielder is choosing to continue lying on the ground, not that he is on the ground as part of a fluid motion from his attempt to catch the ball. Furthermore, a strict liability interpretation is totally inconsistent with the rest of the rulebook -- for example, everybody knows a runner can obstruct a fielder turning a double play if he does so as part of a legitimate act of baserunning, whereas if he goes out of his way (with intent) to unnecessarily interfere with the fielder it is an out. Why would obstruction by the fielder be any different? Umpires botched it and have misinterpreted the rule. I don't blame them because that is a hard call to make in a split second, but they screwed up and are setting bad precedent with their defense of the call.