I don't regret not pursuing either one. With how much is going wrong with this team, I don't think either would be able to put us into contention. I used to be very high on Yu, but in recent years, I've wondered if he might a "good pitcher from the neck down." He has never been very good at working his way out of jams, especially in big games. I also question whether or not he has truly regained confidence in his elbow after Tommy John surgery. It seems like he challenges hitters less and tries to get cute more than he used to. I know his velocity is still solid, but does it really feel the same? I honestly don't know the answer to that.
Arrieta is off to a great start, and he has been pretty good in big games. Furthermore, he's a bit of a bad-*** - the type I'd want in my rotation. However, we're a good 2 - 3 years away from contention, and I think he has an opt-out after 2019. Not much reason to sign him now. If we're on the cusp of contention for 2020 and he opts out, might it make sense to go after him if he's still putting up good numbers? Absolutely.