@MLBReplays is the official MLB instant replay twitter account, it tweets the details of every challenged call.
This site automatically parses @MLBReplays' tweets.

TeamOverturned CallsUpheld CallsChallenge Effectiveness
Umpires Crew48169.779
New York Yankees238.742
Miami Marlins199.679
Atlanta Braves2311.676
Washington Nationals2010.667
Milwaukee Brewers1710.630
San Francisco Giants2416.600
Kansas City Royals2114.600
Houston Astros1913.594
Detroit Tigers2317.575
Seattle Mariners2015.571
Anaheim Angels2116.568
Los Angeles Dodgers2217.564
Cleveland Indians1814.563
Boston Red Sox1915.559
Pittsburgh Pirates2016.556
Texas Rangers2220.524
Minnesota Twins1918.514
Arizona Diamondbacks1919.500
San Diego Padres1616.500
Baltimore Orioles1414.500
Oakland Athletics1414.500
Chicago White Sox1719.472
New York Mets1417.452
Cincinnati Reds1215.444
Tampa Bay Rays2127.438
Chicago Cubs2431.436
Philadelphia Phillies1419.424
St. Louis Cardinals1321.382
Colorado Rockies1423.378
Toronto Blue Jays1630.348