I agree, and on the major league level, I think Megill/Blackburn are actually very good 6th and 7th starters as well. I'm unsure if Megill as any options left, but we would be in a great spot if he's the ace of the Syracuse Mets in April.
I also think Butto is being underestimated as well. He was pitching really well in AAA as a starter. I wouldn't be angry at all if he was slotted in as our fifth starter next year. I don't want him to fall into a Seth Lugo trap, and like him, I don't think he can recover quickly enough in time to be a full-time one anyway. That would be exceptional value as well -- he doesn't even become arb eligible until 2027!
Butto/Senga are probably the best arguments to get a six man rotation going, but especially if we add more injury-prone "prove it" guys as well.