Interestingly, the last time the Braves had a similar year was 1914, when the Boston Braves were in last place halfway through the season, then zoomed up to first, then as the very-much-underdogs beat the Philadelphia Athletics in four straight, the first time a 4-0 World Series had ever happened (cf. here). I wonder whether the ending of game 4 was similar to today, with the Braves celebrating (at Fenway), and the As skulking off to the locker room on their way back to Philly.
“MLB, as far as I can tell, has never had team handshakes after a game or a series.”
From what I’ve seen there are handshakes between members of the same team but not between teams.