Of the 13 MLB games that wound up being played on Opening Day, four went to extra frames. This of course meant that the extra innings rule that's been in place since the start of the 2020 season wound up playing an outsized role on one of baseball's signature days on the calendar. 

For the uninitiated or the willfully forgetful, each half inning beyond the ninth -- i.e., extra innings -- in MLB now begins with a runner on second base and no outs. The damnable specifics from Thursday: 

The Blue Jays topped the Yankees in 10, with that automatic runner scoring the go-ahead run. Randul Grichuk led off the inning with an RBI double. Yes, he led off the inning and tallied an RBI that didn't come on a home run. "Anything is possible" numbers among the greatest lies ever told, but there's something to it in this instance.

The Brewers won on a walk-off fielder's choice when an Orlando Arcia grounder to second plated the automatic runner. 

Bryce Harper served as the Phillies' automatic runner in the 10th inning against the Braves. He advanced to third on a ground ball and then scored the winning run on a Jean Segura single down the line that probably would've been playable had the corners not been in on account of Harper. 

In Seattle, Giants reliever Jose Alvarez in the 10th walked three straight batters to force home the charity runner. 

The idea, which is a sound one, is to cut down on marathon-length tilts that go, say, 13, 14, 19 innings and on rare occasion beyond. Given the ongoing pandemic conditions, this makes sense, and it also makes sense when it comes to avoiding mangling pitching staffs and layering on roster-wide fatigue. It's debatable whether it was necessary to keep the wrinkle intact for the 2021 season, but let's say it is. The danger is that we get conditioned to it, and it becomes a permanent rule in MLB.