Why not use him for seven then LOL. Every out matters for these guys, seriously. The number of pitches.
The thinking was all about the Yankees having the bottom of the order coming up for Barnes. He messed up.
Another thing is, you're hoping Kimbrel preserves the lead and then you score a couple more to take some pressure off him in the bottom of the 9th.
There are always a bunch of variables.
I agree that there is some desperation involved there, born out of really wanting the win and not having a lot of confidence in the bullpen in general.