The thing is, if there were a LH starter who threw 100 mph on the mound, then DS would start against him and bat 2nd. So if he can't hit velocity, then you would think they wouldn't care about a LHP or RHP, they'd focus more on the type of pitcher on the mound. Unless they think he's fine against velocity as long as it's not a RHP, even though as mentioned DS hits RHP better. Maybe there's something in the numbers to suggest that, I don't know. It's just a strange usage. Starting IKF over any competent big leaguer is/was insanity, so I'd like to know their reasoning.
With that said, Lukes since the 2nd half of last season has a 79 wRC+ in 243 PA. Against RHP over that span, it's 73. His BB% over that span around 5%. They got a mirage season out of a journeyman in a "team of destiny" run. We will see how long of a leash Lukes gets based on 2025, but DS should be getting more time over Lukes against RHP with Barger out.