Smallbone was selected ahead of Lesley Ugochukwu, but was substituted on 56 minutes, with him being barracked by home fans.
"Lesley is a young guy who has had to play always and I had a feeling that he had to rest a little bit," explained Juric, speaking to the Daily Echo.
"I wanted to give the chance to Will because he's training hard, that's it. They (Smallbone and Aribo) didn't work. I think they can play better.
"Aribo playing as a left-centre-back did a great second half. It's obvious that if we want to play like this, we need more dynamic players.
"Two times now he did really well playing left-centre-back. In the middle, with Lesley and even with Mateus Fernandes, we were doing much better."
He added, "He's a great guy, an incredible professional. He gives everything he has. I'm disappointed that he didn't play well.
"I'm not angry with him, I'm just disappointed because he's really a guy who gives everything on the training pitch.
"I expected more, it's obvious, but I'm really sorry for him because he doesn't deserve it. He's a good guy."