Following is a link to a PDF article by MGL, in which he presents an outstanding analysis of Questec, and its impact on the strike zone.
In it, MGL concludes that the presence of Questec, that robotic supervisor of umpires, does indeed shrink the strike zone. His conclusion is based on an analysis of balls and strikes before and after the introduction of Questec, including an adjustment for each park. One thing we often forget is that ballparks have inherently different strikeout rates, due to visibility and other factors, and MGL’s analysis takes this into account.
Questec was employed in ten ballparks last year, with a handful to be added this year. To read more about Questec, you can read last month’s article from SI’s Tom Verducci.