In the early innings of ALCS Game 7 between the Yankees and Astros (NYY-HOU GameTracker), Houston starter Charlie Morton appeared on multiple occasions to dab his pitching fingers against his chewing gum.
See here, for instance ...
Charlie “Stickie Fingers” Morton #astros #yankees pic.twitter.com/WOzBmTxzuX
— Igor Mello (@SuperIgor) October 22, 2017
And there's also this from his Game 3 start ...
Umm Charlie Morton, I don't think touching your gum and then pitching is legal. pic.twitter.com/dLwASu8Tkm
— Chris Hall (@bestinthegame2) October 17, 2017
Pitchers, of course, are not allowed to use any foreign substance in such a manner. That's perhaps why Yankees manager Joe Girardi, during a stoppage in play, had a conversation with plate ump Mark Carlson, who subsequently spoke with both Morton and Astros manager A.J. Hinch.
Obviously, both managers will likely be asked about this sequence of events in their post-game pressers. Either way, Morton's days of gum-chewing on the mound may be over.