you've got your ace on the mound, and a three run lead after the grand slam in the fourth inning, and you know you have another game to play later in the day. I think because it was our ace, we decided to go with him as long as we could especially since we had the lead. I would imagine that because of how early it was in the game that we had no one warming up especially with a lead that big.
Cohen probably left him in simply because no one was ready, we still had the lead, were hitting well, and had another game left to play. And you can't really say "Well why didn't Cohen have someone ready in the bullpen"- because when you have another game and a lead like that you have to try to conserve your bullpen as much as possible.
It's unfortuante for us how it played out.
I'm not blaming or deflecting the blame from anyone, just trying to tell what I think was going through the coaches head.