Boston catcher David Ross' throw beat Jennings to the base, but Dustin Pedroia's tag was too high on Jennings' arm, and the Tampa Bay center fielder's hand got in ahead of it.
"I probably would have argued that straight up in the past," Maddon said after the game -- meaning before the advent of the challenge system.
It's a play he could have argued until he was blue in the face, and it would never have gotten overturned. It's also a play that, before challenges, umpires would almost invariably call "out" on -- the throw beat the runner and the tag was put down quickly.
"For the last hundred years, every one of those guys would've been out," Maddon said.
But with the new replay review system, umpires can't give the benefit of the doubt to the fielder on those plays -- or, if they do, managers can challenge the call. So fielders have to follow the letter of the rules and get tags down -- contrary to, for example, the neighborhood play, which is unchallengable and in which fielders still have leeway.
"Tagging is going to have to be taken to another level," Maddon said. "Seriously. There's been a lot of assumptionism in tagging.
"I think as we move forward, teaching guys how to tag runners better is going to become more of a premium -- not only tagging them initially, but holding tags longer, because of the fact that if the guy comes off the bag, he can be out now with the replay.
"That part probably wasn't spoken about enough in regard to the instant replay."
David Adler is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.