I don't think Cristobal or Taggart were good hires. This was Oregon 5th loss by double digits this year.
Taggart was a very good hire. Helfrich had run the program into the ground. Recruiting had been shoddy, so its not like Taggart was taking over a top ten program. He had put together a fantastic coaching staff and was on the verge of signing the best recruiting class in school history. It also didnt help matters when Herbert got injured and missed pretty much the entire season.
This is why it's bad for new coaches to coach the bowl game. If you lose, you suck. It was a horrible hire, etc. etc.
You're correct that it is not a good idea for a new coach to coach in the bowl game. However, Cristobal was the OC and was promoted to interim head coach when Taggart left. Oregon decided to remove the interim tag and hire him to replace Taggart. Therefore, he was coaching in the bowl either way.