Honestly, I could see the decision either way. O’Hearn is a hot hitter historically vulnerable to lefties. Hays historically hits lefties well but has been as cold as you can get. He’s a significant defensive upgrade to O’Hearn for the rest of the game. So what do you do?
If my only concern was to maximize the chance to win today’s game, I’d probably stick with O’Hearn, for a reason not mentioned yet. This was the leadoff batter in the 7th inning, and if anyone gets on base the next three innings, that means the batter will get one more AB after the one in the 7th inning, and decent chance that AB will be against a RHP. So, that favors leaving O’Hearn in.
At the same time, I don’t believe that maximizing the chance to win this game was the only consideration. Simply put, Hyde wants to keep Hays involved in things, and wants to give him opportunities to break out of his slump. And that’s important for the long term benefit of the team.
So, as I see it, it’s a close call, and I wouldn’t criticize Hyde either way. We won the game so I’m certainly not going to obsess about it.