Home plate umpires are getting better. Will that hold off the robots?
Umpire Assignments Announced for 2018 Little League® Southeast Region Tournaments - Little League
Ten MLB Umpires Retiring, Most Since 1999
West High grad takes step up in career behind the plate, Tracy Press sports
Jason Marquis - Wikipedia
The Past, Present and Future of Baseball in Puerto Rico
10 MLB Umpires Retire - Baseball Says Bye to 261 Years of On-Field Major League Umpiring Experience
Gread McKinnis – Society for American Baseball Research
MLB Rule Changes: Atlantic League Tests Tweaks Meant to Save Baseball - Bloomberg
Major League Baseball's umpire retired numbers
Sources - 10 MLB umps retiring, most since '99 - ESPN
MLB Revamps Umpire Staff; 10 Umpires Decide It's Time For Retirement — Inside the Seams
A Large Number of Veteran MLB Umpires Are Retiring - Bleacher Nation
Returning to Music City after 10 years with the Titans is weird for Falcons coach Arthur Smith, Football