In the third inning of the Cardinals eventual loss to the Reds on Wednesday night (CIN 4, STL 2), St. Louis starter John Lackey was ejected mid-batter by plate ump Tom Hallion, apparently for arguing balls and strikes. 

The MLB.com video of the incident isn't embeddable, but here's a GIF of the sequence in question ... 

Lackey did not appear to have much in the way of a legitimate complaint inasmuch as the pitch just prior to his ejection is concerned, but the guess here is that this wasn't the first time that Lackey expressed his displeasure over Hallion's zone. Unless you were within earshot, there's no way to know whether the ejection was justified, but running a contending team's starting pitcher in September for something like this certainly qualifies as "aggressive umpiring."

For what it's worth, Lackey's replacement, Tyler Lyons, gave up two runs in 2 1/13 innings and bunted into a critical double play.